1
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Weng Q, Wan L, Straker GC, Deegan TD, Duncker BP, Neiman AM, Luk E, Hollingsworth NM. An acidic loop in the FHA domain of the yeast meiosis-specific kinase Mek1 interacts with a specific motif in a subset of Mek1 substrates. Genetics 2024:iyae106. [PMID: 38979911 DOI: 10.1093/genetics/iyae106] [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: 05/24/2024] [Revised: 06/27/2024] [Accepted: 06/28/2024] [Indexed: 07/10/2024] Open
Abstract
The meiosis-specific kinase Mek1 regulates key steps in meiotic recombination in the budding yeast, Saccharomyces cerevisiae. MEK1 limits resection at double strand break (DSB) ends and is required for preferential strand invasion into homologs, a process known as interhomolog bias. After strand invasion, MEK1 promotes phosphorylation of the synaptonemal complex protein Zip1 that is necessary for DSB repair mediated by a crossover specific pathway that enables chromosome synapsis. In addition, Mek1 phosphorylation of the meiosis-specific transcription factor, Ndt80, regulates the meiotic recombination checkpoint that prevents exit from pachytene when DSBs are present. Mek1 interacts with Ndt80 through a five amino acid sequence, RPSKR, located between the DNA binding and activation domains of Ndt80. AlphaFold Multimer modeling of a fragment of Ndt80 containing the RPSKR motif and full length Mek1 indicated that RPSKR binds to an acidic loop located in the Mek1 FHA domain, a non-canonical interaction with this motif. A second protein, the 5'-3' helicase Rrm3, similarly interacts with Mek1 through an RPAKR motif and is an in vitro substrate of Mek1. Genetic analysis using various mutants in the MEK1 acidic loop validated the AlphaFold model, in that they specifically disrupt two-hybrid interactions with Ndt80 and Rrm3. Phenotypic analyses further showed that the acidic loop mutants are defective in the meiotic recombination checkpoint, and in certain circumstances exhibit more severe phenotypes compared to the NDT80 mutant with the RPSKR sequence deleted, suggesting that additional, as yet unknown, substrates of Mek1 also bind to Mek1 using an RPXKR motif.
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Affiliation(s)
- Qixuan Weng
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Lihong Wan
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Geburah C Straker
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
| | - Tom D Deegan
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, UK DD1 5EH, UK
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Bernard P Duncker
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
| | - Aaron M Neiman
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Ed Luk
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Nancy M Hollingsworth
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
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2
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Lama-Diaz T, Blanco MG. Alternative translation initiation by ribosomal leaky scanning produces multiple isoforms of the Pif1 helicase. Nucleic Acids Res 2024; 52:6928-6944. [PMID: 38783074 PMCID: PMC11229318 DOI: 10.1093/nar/gkae400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 04/24/2024] [Accepted: 05/01/2024] [Indexed: 05/25/2024] Open
Abstract
In budding yeast, the integrity of both the nuclear and mitochondrial genomes relies on dual-targeted isoforms of the conserved Pif1 helicase, generated by alternative translation initiation (ATI) of PIF1 mRNA from two consecutive AUG codons flanking a mitochondrial targeting signal. Here, we demonstrate that ribosomal leaky scanning is the specific ATI mechanism that produces not only these, but also novel, previously uncharacterized Pif1 isoforms. Both in-frame, downstream AUGs as well as near-cognate start codons contribute to the generation of these alternative isoforms. This has crucial implications for the rational design of genuine separation-of-function alleles and provides an explanation for the suboptimal behaviour of the widely employed mitochondrial- (pif1-m1) and nuclear-deficient (pif1-m2) alleles, with mutations in the first or second AUG codon, respectively. We have taken advantage of this refined model to develop improved versions of these alleles, which will serve as valuable tools to elucidate novel functions of this helicase and to disambiguate previously described genetic interactions of PIF1 in the context of nuclear and mitochondrial genome stability.
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Affiliation(s)
- Tomas Lama-Diaz
- Department of Biochemistry and Molecular Biology, CIMUS, Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, A Coruña 15782, Spain
| | - Miguel G Blanco
- Department of Biochemistry and Molecular Biology, CIMUS, Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, A Coruña 15782, Spain
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3
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Weng Q, Wan L, Straker GC, Deegan TD, Duncker BP, Neiman AM, Luk E, Hollingsworth NM. An acidic loop in the FHA domain of the yeast meiosis-specific kinase Mek1 interacts with a specific motif in a subset of Mek1 substrates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.24.595751. [PMID: 38826409 PMCID: PMC11142242 DOI: 10.1101/2024.05.24.595751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
The meiosis-specific kinase Mek1 regulates key steps in meiotic recombination in the budding yeast, Saccharomyces cerevisiae. MEK1 limits resection at the double strand break (DSB) ends and is required for preferential strand invasion into homologs, a process known as interhomolog bias. After strand invasion, MEK1 promotes phosphorylation of the synaptonemal complex protein Zip1 that is necessary for DSB repair mediated by a crossover specific pathway that enables chromosome synapsis. In addition, Mek1 phosphorylation of the meiosis-specific transcription factor, Ndt80, regulates the meiotic recombination checkpoint that prevents exit from pachytene when DSBs are present. Mek1 interacts with Ndt80 through a five amino acid sequence, RPSKR, located between the DNA binding and activation domains of Ndt80. AlphaFold Multimer modeling of a fragment of Ndt80 containing the RPSKR motif and full length Mek1 indicated that RPSKR binds to an acidic loop located in the Mek1 FHA domain, a non-canonical interaction with this motif. A second protein, the 5'-3' helicase Rrm3, similarly interacts with Mek1 through an RPAKR motif and is an in vitro substrate of Mek1. Genetic analysis using various mutants in the MEK1 acidic loop validated the AlphaFold model, in that they specifically disrupt two-hybrid interactions with Ndt80 and Rrm3. Phenotypic analyses further showed that the acidic loop mutants are defective in the meiotic recombination checkpoint, and in certain circumstances exhibit more severe phenotypes compared to the NDT80 mutant with the RPSKR sequence deleted, suggesting that additional, as yet unknown, substrates of Mek1 also bind to Mek1 using an RPXKR motif.
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Affiliation(s)
- Qixuan Weng
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Lihong Wan
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Geburah C. Straker
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
| | - Tom. D. Deegan
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, UK DD1 5EH, UK
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Bernard P. Duncker
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
| | - Aaron M. Neiman
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Ed Luk
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Nancy M. Hollingsworth
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
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4
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Bugallo A, Sánchez M, Fernández-García M, Segurado M. S-phase checkpoint prevents leading strand degradation from strand-associated nicks at stalled replication forks. Nucleic Acids Res 2024; 52:5121-5137. [PMID: 38520409 PMCID: PMC11109941 DOI: 10.1093/nar/gkae192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 03/01/2024] [Accepted: 03/07/2024] [Indexed: 03/25/2024] Open
Abstract
The S-phase checkpoint is involved in coupling DNA unwinding with nascent strand synthesis and is critical to maintain replication fork stability in conditions of replicative stress. However, its role in the specific regulation of leading and lagging strands at stalled forks is unclear. By conditionally depleting RNaseH2 and analyzing polymerase usage genome-wide, we examine the enzymology of DNA replication during a single S-phase in the presence of replicative stress and show that there is a differential regulation of lagging and leading strands. In checkpoint proficient cells, lagging strand replication is down-regulated through an Elg1-dependent mechanism. Nevertheless, when checkpoint function is impaired we observe a defect specifically at the leading strand, which was partially dependent on Exo1 activity. Further, our genome-wide mapping of DNA single-strand breaks reveals that strand discontinuities highly accumulate at the leading strand in HU-treated cells, whose dynamics are affected by checkpoint function and Exo1 activity. Our data reveal an unexpected role of Exo1 at the leading strand and support a model of fork stabilization through prevention of unrestrained Exo1-dependent resection of leading strand-associated nicks after fork stalling.
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Affiliation(s)
- Alberto Bugallo
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - Mar Sánchez
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - María Fernández-García
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - Mónica Segurado
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
- Departamento de Microbiología y Genética (USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
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5
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Kotenko O, Makovets S. The functional significance of the RPA- and PCNA-dependent recruitment of Pif1 to DNA. EMBO Rep 2024; 25:1734-1751. [PMID: 38480846 PMCID: PMC11014909 DOI: 10.1038/s44319-024-00114-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 02/10/2024] [Accepted: 02/26/2024] [Indexed: 04/14/2024] Open
Abstract
Pif1 family helicases are multifunctional proteins conserved in eukaryotes, from yeast to humans. They are important for the genome maintenance in both nuclei and mitochondria, where they have been implicated in Okazaki fragment processing, replication fork progression and termination, telomerase regulation and DNA repair. While the Pif1 helicase activity is readily detectable on naked nucleic acids in vitro, the in vivo functions rely on recruitment to DNA. We identify the single-stranded DNA binding protein complex RPA as the major recruiter of Pif1 in budding yeast, in addition to the previously reported Pif1-PCNA interaction. The two modes of the Pif1 recruitment act independently during telomerase inhibition, as the mutations in the Pif1 motifs disrupting either of the recruitment pathways act additively. In contrast, both recruitment mechanisms are essential for the replication-related roles of Pif1 at conventional forks and during the repair by break-induced replication. We propose a molecular model where RPA and PCNA provide a double anchoring of Pif1 at replication forks, which is essential for the Pif1 functions related to the fork movement.
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Affiliation(s)
- Oleksii Kotenko
- Institute of Cell Biology, University of Edinburgh, King's Buildings, Alexander Crum Brown Road, Edinburgh, EH9 3FF, UK
| | - Svetlana Makovets
- Institute of Cell Biology, University of Edinburgh, King's Buildings, Alexander Crum Brown Road, Edinburgh, EH9 3FF, UK.
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6
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Khatib JB, Nicolae CM, Moldovan GL. Role of Translesion DNA Synthesis in the Metabolism of Replication-associated Nascent Strand Gaps. J Mol Biol 2024; 436:168275. [PMID: 37714300 PMCID: PMC10842951 DOI: 10.1016/j.jmb.2023.168275] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/11/2023] [Accepted: 09/08/2023] [Indexed: 09/17/2023]
Abstract
Translesion DNA synthesis (TLS) is a DNA damage tolerance pathway utilized by cells to overcome lesions encountered throughout DNA replication. During replication stress, cancer cells show increased dependency on TLS proteins for cellular survival and chemoresistance. TLS proteins have been described to be involved in various DNA repair pathways. One of the major emerging roles of TLS is single-stranded DNA (ssDNA) gap-filling, primarily after the repriming activity of PrimPol upon encountering a lesion. Conversely, suppression of ssDNA gap accumulation by TLS is considered to represent a mechanism for cancer cells to evade the toxicity of chemotherapeutic agents, specifically in BRCA-deficient cells. Thus, TLS inhibition is emerging as a potential treatment regimen for DNA repair-deficient tumors.
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Affiliation(s)
- Jude B Khatib
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA. https://twitter.com/JudeBKhatib
| | - Claudia M Nicolae
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
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7
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Ivessa AS, Singh S. The increase in cell death rates in caloric restricted cells of the yeast helicase mutant rrm3 is Sir complex dependent. Sci Rep 2023; 13:17832. [PMID: 37857740 PMCID: PMC10587150 DOI: 10.1038/s41598-023-45125-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 10/16/2023] [Indexed: 10/21/2023] Open
Abstract
Calorie restriction (CR), which is a reduction in calorie intake without malnutrition, usually extends lifespan and improves tissue integrity. This report focuses on the relationship between nuclear genomic instability and dietary-restriction and its effect on cell survival. We demonstrate that the cell survival rates of the genomic instability yeast mutant rrm3 change under metabolic restricted conditions. Rrm3 is a DNA helicase, chromosomal replication slows (and potentially stalls) in its absence with increased rates at over 1400 natural pause sites including sites within ribosomal DNA and tRNA genes. Whereas rrm3 mutant cells have lower cell death rates compared to wild type (WT) in growth medium containing normal glucose levels (i.e., 2%), under CR growth conditions cell death rates increase in the rrm3 mutant to levels, which are higher than WT. The silent-information-regulatory (Sir) protein complex and mitochondrial oxidative stress are required for the increase in cell death rates in the rrm3 mutant when cells are transferred from growth medium containing 2% glucose to CR-medium. The Rad53 checkpoint protein is highly phosphorylated in the rrm3 mutant in response to genomic instability in growth medium containing 2% glucose. Under CR, Rad53 phosphorylation is largely reduced in the rrm3 mutant in a Sir-complex dependent manner. Since CR is an adjuvant treatment during chemotherapy, which may target genomic instability in cancer cells, our studies may gain further insight into how these therapy strategies can be improved.
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Affiliation(s)
- Andreas S Ivessa
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, Rutgers Biomedical and Health Sciences, 185 South Orange Avenue, Newark, NJ, 07101-1709, USA.
| | - Sukhwinder Singh
- Pathology and Laboratory Medicine/Flow Cytometry and Immunology Core Laboratory, Rutgers New Jersey Medical School, Rutgers Biomedical and Health Sciences, 185 South Orange Avenue, Newark, NJ, 07101-1709, USA
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8
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Choudhary R, Niska-Blakie J, Adhil M, Liberi G, Achar YJ, Giannattasio M, Foiani M. Sen1 and Rrm3 ensure permissive topological conditions for replication termination. Cell Rep 2023; 42:112747. [PMID: 37405920 DOI: 10.1016/j.celrep.2023.112747] [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: 10/01/2022] [Revised: 04/17/2023] [Accepted: 06/20/2023] [Indexed: 07/07/2023] Open
Abstract
Replication forks terminate at TERs and telomeres. Forks that converge or encounter transcription generate topological stress. Combining genetics, genomics, and transmission electron microscopy, we find that Rrm3hPif1 and Sen1hSenataxin helicases assist termination at TERs; Sen1 specifically acts at telomeres. rrm3 and sen1 genetically interact and fail to terminate replication, exhibiting fragility at termination zones (TERs) and telomeres. sen1rrm3 accumulates RNA-DNA hybrids and X-shaped gapped or reversed converging forks at TERs; sen1, but not rrm3, builds up RNA polymerase II (RNPII) at TERs and telomeres. Rrm3 and Sen1 restrain Top1 and Top2 activities, preventing toxic accumulation of positive supercoil at TERs and telomeres. We suggest that Rrm3 and Sen1 coordinate the activities of Top1 and Top2 when forks encounter transcription head on or codirectionally, respectively, thus preventing the slowing down of DNA and RNA polymerases. Hence Rrm3 and Sen1 are indispensable to generate permissive topological conditions for replication termination.
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Affiliation(s)
- Ramveer Choudhary
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Joanna Niska-Blakie
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Mohamood Adhil
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Giordano Liberi
- Istituto di Genetica Molecolare "Luigi Luca Cavalli-Sforza," CNR, Pavia, Italy
| | | | - Michele Giannattasio
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, Via Festa del Perdono, 7, 20122 Milan, Italy
| | - Marco Foiani
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, Via Festa del Perdono, 7, 20122 Milan, Italy.
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9
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Muellner J, Schmidt KH. Helicase activities of Rad5 and Rrm3 genetically interact in the prevention of recombinogenic DNA lesions in Saccharomyces cerevisiae. DNA Repair (Amst) 2023; 126:103488. [PMID: 37054652 PMCID: PMC10399609 DOI: 10.1016/j.dnarep.2023.103488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 03/09/2023] [Accepted: 03/28/2023] [Indexed: 03/31/2023]
Abstract
The genome must be monitored to ensure its duplication is completed accurately to prevent genome instability. In Saccharomyces cerevisiae, the 5' to 3' DNA helicase Rrm3, a member of the conserved PIF1 family, facilitates replication fork progression through an unknown mechanism. Disruption of Rrm3 helicase activity leads to increased replication fork pausing throughout the yeast genome. Here, we show that Rrm3 contributes to replication stress tolerance in the absence of the fork reversal activity of Rad5, defined by its HIRAN domain and DNA helicase activity, but not in the absence of Rad5's ubiquitin ligase activity. The Rrm3 and Rad5 helicase activities also interact in the prevention of recombinogenic DNA lesions, and DNA lesions that accumulate in their absence need to be salvaged by a Rad59-dependent recombination pathway. Disruption of the structure-specific endonuclease Mus81 leads to accumulation of recombinogenic DNA lesions and chromosomal rearrangements in the absence of Rrm3, but not Rad5. Thus, at least two mechanisms exist to overcome fork stalling at replication barriers, defined by Rad5-mediated fork reversal and Mus81-mediated cleavage, and contribute to the maintenance of chromosome stability in the absence of Rrm3.
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Affiliation(s)
- Julius Muellner
- Department of Molecular Biosciences, University of South Florida, Tampa, FL 33620, United States; Graduate program in Cell and Molecular Biology, University of South Florida, Tampa, FL 33620, United States
| | - Kristina H Schmidt
- Department of Molecular Biosciences, University of South Florida, Tampa, FL 33620, United States; Graduate program in Cell and Molecular Biology, University of South Florida, Tampa, FL 33620, United States; Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, United States.
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10
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Gordon MR, Zhu J, Sun G, Li R. Suppression of chromosome instability by targeting a DNA helicase in budding yeast. Mol Biol Cell 2023; 34:ar3. [PMID: 36350688 PMCID: PMC9816644 DOI: 10.1091/mbc.e22-09-0395] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 11/04/2022] [Indexed: 11/10/2022] Open
Abstract
Chromosome instability (CIN) is an important driver of cancer initiation, progression, drug resistance, and aging. As such, genes whose inhibition suppresses CIN are potential therapeutic targets. We report here that deletion of an accessory DNA helicase, Rrm3, suppresses high CIN caused by a wide range of genetic or pharmacological perturbations in yeast. Although this helicase mutant has altered cell cycle dynamics, suppression of CIN by rrm3∆ is independent of the DNA damage and spindle assembly checkpoints. Instead, the rrm3∆ mutant may have increased kinetochore-microtubule error correction due to an altered localization of Aurora B kinase and associated phosphatase, PP2A-Rts1.
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Affiliation(s)
- Molly R. Gordon
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Jin Zhu
- Mechanobiology Institute and
| | - Gordon Sun
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Department of Biomedical Engineering and
| | - Rong Li
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Mechanobiology Institute and
- Department of Biological Sciences, National University of Singapore, 117411
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218
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11
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A DNA Replication Fork-centric View of the Budding Yeast DNA Damage Response. DNA Repair (Amst) 2022; 119:103393. [DOI: 10.1016/j.dnarep.2022.103393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 11/23/2022]
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12
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Post-Translational Modifications of PCNA: Guiding for the Best DNA Damage Tolerance Choice. J Fungi (Basel) 2022; 8:jof8060621. [PMID: 35736104 PMCID: PMC9225081 DOI: 10.3390/jof8060621] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/01/2022] [Accepted: 06/07/2022] [Indexed: 02/01/2023] Open
Abstract
The sliding clamp PCNA is a multifunctional homotrimer mainly linked to DNA replication. During this process, cells must ensure an accurate and complete genome replication when constantly challenged by the presence of DNA lesions. Post-translational modifications of PCNA play a crucial role in channeling DNA damage tolerance (DDT) and repair mechanisms to bypass unrepaired lesions and promote optimal fork replication restart. PCNA ubiquitination processes trigger the following two main DDT sub-pathways: Rad6/Rad18-dependent PCNA monoubiquitination and Ubc13-Mms2/Rad5-mediated PCNA polyubiquitination, promoting error-prone translation synthesis (TLS) or error-free template switch (TS) pathways, respectively. However, the fork protection mechanism leading to TS during fork reversal is still poorly understood. In contrast, PCNA sumoylation impedes the homologous recombination (HR)-mediated salvage recombination (SR) repair pathway. Focusing on Saccharomyces cerevisiae budding yeast, we summarized PCNA related-DDT and repair mechanisms that coordinately sustain genome stability and cell survival. In addition, we compared PCNA sequences from various fungal pathogens, considering recent advances in structural features. Importantly, the identification of PCNA epitopes may lead to potential fungal targets for antifungal drug development.
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13
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Yeast Stn1 promotes MCM to circumvent Rad53 control of the S phase checkpoint. Curr Genet 2022; 68:165-179. [PMID: 35150303 PMCID: PMC8976814 DOI: 10.1007/s00294-022-01228-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 12/06/2021] [Accepted: 12/16/2021] [Indexed: 11/17/2022]
Abstract
Treating yeast cells with the replication inhibitor hydroxyurea activates the S phase checkpoint kinase Rad53, eliciting responses that block DNA replication origin firing, stabilize replication forks, and prevent premature extension of the mitotic spindle. We previously found overproduction of Stn1, a subunit of the telomere-binding Cdc13–Stn1–Ten1 complex, circumvents Rad53 checkpoint functions in hydroxyurea, inducing late origin firing and premature spindle extension even though Rad53 is activated normally. Here, we show Stn1 overproduction acts through remarkably similar pathways compared to loss of RAD53, converging on the MCM complex that initiates origin firing and forms the catalytic core of the replicative DNA helicase. First, mutations affecting Mcm2 and Mcm5 block the ability of Stn1 overproduction to disrupt the S phase checkpoint. Second, loss of function stn1 mutations compensate rad53 S phase checkpoint defects. Third Stn1 overproduction suppresses a mutation in Mcm7. Fourth, stn1 mutants accumulate single-stranded DNA at non-telomeric genome locations, imposing a requirement for post-replication DNA repair. We discuss these interactions in terms of a model in which Stn1 acts as an accessory replication factor that facilitates MCM activation at ORIs and potentially also maintains MCM activity at replication forks advancing through challenging templates.
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14
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Rajapaksha P, Simmons RH, Gray SJ, Sun DJ, Nguyen P, Nickens DG, Bochman ML. Bulk phase biochemistry of PIF1 and RecQ4 family helicases. Methods Enzymol 2022; 673:169-190. [DOI: 10.1016/bs.mie.2022.03.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Hydroxyurea-The Good, the Bad and the Ugly. Genes (Basel) 2021; 12:genes12071096. [PMID: 34356112 PMCID: PMC8304116 DOI: 10.3390/genes12071096] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 07/13/2021] [Accepted: 07/16/2021] [Indexed: 01/23/2023] Open
Abstract
Hydroxyurea (HU) is mostly referred to as an inhibitor of ribonucleotide reductase (RNR) and as the agent that is commonly used to arrest cells in the S-phase of the cycle by inducing replication stress. It is a well-known and widely used drug, one which has proved to be effective in treating chronic myeloproliferative disorders and which is considered a staple agent in sickle anemia therapy and—recently—a promising factor in preventing cognitive decline in Alzheimer’s disease. The reversibility of HU-induced replication inhibition also makes it a common laboratory ingredient used to synchronize cell cycles. On the other hand, prolonged treatment or higher dosage of hydroxyurea causes cell death due to accumulation of DNA damage and oxidative stress. Hydroxyurea treatments are also still far from perfect and it has been suggested that it facilitates skin cancer progression. Also, recent studies have shown that hydroxyurea may affect a larger number of enzymes due to its less specific interaction mechanism, which may contribute to further as-yet unspecified factors affecting cell response. In this review, we examine the actual state of knowledge about hydroxyurea and the mechanisms behind its cytotoxic effects. The practical applications of the recent findings may prove to enhance the already existing use of the drug in new and promising ways.
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16
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Checkpoint-mediated DNA polymerase ε exonuclease activity curbing counteracts resection-driven fork collapse. Mol Cell 2021; 81:2778-2792.e4. [PMID: 33932350 PMCID: PMC7612761 DOI: 10.1016/j.molcel.2021.04.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 04/06/2021] [Accepted: 04/08/2021] [Indexed: 02/01/2023]
Abstract
DNA polymerase ε (Polε) carries out high-fidelity leading strand synthesis owing to its exonuclease activity. Polε polymerase and exonuclease activities are balanced, because of partitioning of nascent DNA strands between catalytic sites, so that net resection occurs when synthesis is impaired. In vivo, DNA synthesis stalling activates replication checkpoint kinases, which act to preserve the functional integrity of replication forks. We show that stalled Polε drives nascent strand resection causing fork functional collapse, averted via checkpoint-dependent phosphorylation. Polε catalytic subunit Pol2 is phosphorylated on serine 430, influencing partitioning between polymerase and exonuclease active sites. A phosphormimetic S430D change reduces exonucleolysis in vitro and counteracts fork collapse. Conversely, non-phosphorylatable pol2-S430A expression causes resection-driven stressed fork defects. Our findings reveal that checkpoint kinases switch Polε to an exonuclease-safe mode preventing nascent strand resection and stabilizing stalled replication forks. Elective partitioning suppression has implications for the diverse Polε roles in genome integrity maintenance.
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17
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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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18
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Xing P, Dong Y, Zhao J, Zhou Z, Li Z, Wang Y, Li M, Zhang X, Chen X. Mrc1-Dependent Chromatin Compaction Represses DNA Double-Stranded Break Repair by Homologous Recombination Upon Replication Stress. Front Cell Dev Biol 2021; 9:630777. [PMID: 33681209 PMCID: PMC7928320 DOI: 10.3389/fcell.2021.630777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 01/06/2021] [Indexed: 11/13/2022] Open
Abstract
The coordination of DNA replication and repair is critical for the maintenance of genome stability. It has been shown that the Mrc1-mediated S phase checkpoint inhibits DNA double-stranded break (DSB) repair through homologous recombination (HR). How the replication checkpoint inhibits HR remains only partially understood. Here we show that replication stress induces the suppression of both Sgs1/Dna2- and Exo1-mediated resection pathways in an Mrc1-dependent manner. As a result, the loading of the single-stranded DNA binding factor replication protein A (RPA) and Rad51 and DSB repair by HR were severely impaired under replication stress. Notably, the deletion of MRC1 partially restored the recruitment of resection enzymes, DSB end resection, and the loading of RPA and Rad51. The role of Mrc1 in inhibiting DSB end resection is independent of Csm3, Tof1, or Ctf4. Mechanistically, we reveal that replication stress induces global chromatin compaction in a manner partially dependent on Mrc1, and this chromatin compaction limits the access of chromatin remodeling factors and HR proteins, leading to the suppression of HR. Our study reveals a critical role of the Mrc1-dependent chromatin structure change in coordinating DNA replication and recombination under replication stress.
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Affiliation(s)
- Poyuan Xing
- Hubei Key Laboratory of Cell Homeostasis and the Institute for Advanced Studies, College of Life Sciences, Wuhan University, Wuhan, China
| | - Yang Dong
- Hubei Key Laboratory of Cell Homeostasis and the Institute for Advanced Studies, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jingyu Zhao
- Hubei Key Laboratory of Cell Homeostasis and the Institute for Advanced Studies, College of Life Sciences, Wuhan University, Wuhan, China
| | - Zhou Zhou
- Hubei Key Laboratory of Cell Homeostasis and the Institute for Advanced Studies, College of Life Sciences, Wuhan University, Wuhan, China
| | - Zhao Li
- Hubei Key Laboratory of Cell Homeostasis and the Institute for Advanced Studies, College of Life Sciences, Wuhan University, Wuhan, China
| | - Yu Wang
- Hubei Key Laboratory of Cell Homeostasis and the Institute for Advanced Studies, College of Life Sciences, Wuhan University, Wuhan, China
| | - Mengfei Li
- Hubei Key Laboratory of Cell Homeostasis and the Institute for Advanced Studies, College of Life Sciences, Wuhan University, Wuhan, China
| | - Xinghua Zhang
- Hubei Key Laboratory of Cell Homeostasis and the Institute for Advanced Studies, College of Life Sciences, Wuhan University, Wuhan, China
| | - Xuefeng Chen
- Hubei Key Laboratory of Cell Homeostasis and the Institute for Advanced Studies, College of Life Sciences, Wuhan University, Wuhan, China
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19
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Lanz MC, Yugandhar K, Gupta S, Sanford EJ, Faça VM, Vega S, Joiner AMN, Fromme JC, Yu H, Smolka MB. In-depth and 3-dimensional exploration of the budding yeast phosphoproteome. EMBO Rep 2021; 22:e51121. [PMID: 33491328 PMCID: PMC7857435 DOI: 10.15252/embr.202051121] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 11/30/2020] [Accepted: 12/03/2020] [Indexed: 01/11/2023] Open
Abstract
Phosphorylation is one of the most dynamic and widespread post-translational modifications regulating virtually every aspect of eukaryotic cell biology. Here, we assemble a dataset from 75 independent phosphoproteomic experiments performed in our laboratory using Saccharomyces cerevisiae. We report 30,902 phosphosites identified from cells cultured in a range of DNA damage conditions and/or arrested in distinct cell cycle stages. To generate a comprehensive resource for the budding yeast community, we aggregate our dataset with the Saccharomyces Genome Database and another recently published study, resulting in over 46,000 budding yeast phosphosites. With the goal of enhancing the identification of functional phosphorylation events, we perform computational positioning of phosphorylation sites on available 3D protein structures and systematically identify events predicted to regulate protein complex architecture. Results reveal hundreds of phosphorylation sites mapping to or near protein interaction interfaces, many of which result in steric or electrostatic "clashes" predicted to disrupt the interaction. With the advancement of Cryo-EM and the increasing number of available structures, our approach should help drive the functional and spatial exploration of the phosphoproteome.
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Affiliation(s)
- Michael C Lanz
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
- Present address:
Department of BiologyStanford UniversityStanfordCAUSA
| | - Kumar Yugandhar
- Department of Computational BiologyWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Shagun Gupta
- Department of Computational BiologyWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Ethan J Sanford
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Vitor M Faça
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Stephanie Vega
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Aaron M N Joiner
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - J Christopher Fromme
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Haiyuan Yu
- Department of Computational BiologyWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Marcus B Smolka
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
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20
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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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21
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Morafraile EC, Bugallo A, Carreira R, Fernández M, Martín-Castellanos C, Blanco MG, Segurado M. Exo1 phosphorylation inhibits exonuclease activity and prevents fork collapse in rad53 mutants independently of the 14-3-3 proteins. Nucleic Acids Res 2020; 48:3053-3070. [PMID: 32020204 PMCID: PMC7102976 DOI: 10.1093/nar/gkaa054] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/15/2020] [Accepted: 01/20/2020] [Indexed: 01/04/2023] Open
Abstract
The S phase checkpoint is crucial to maintain genome stability under conditions that threaten DNA replication. One of its critical functions is to prevent Exo1-dependent fork degradation, and Exo1 is phosphorylated in response to different genotoxic agents. Exo1 seemed to be regulated by several post-translational modifications in the presence of replicative stress, but the specific contribution of checkpoint-dependent phosphorylation to Exo1 control and fork stability is not clear. We show here that Exo1 phosphorylation is Dun1-independent and Rad53-dependent in response to DNA damage or dNTP depletion, and in both situations Exo1 is similarly phosphorylated at multiple sites. To investigate the correlation between Exo1 phosphorylation and fork stability, we have generated phospho-mimic exo1 alleles that rescue fork collapse in rad53 mutants as efficiently as exo1-nuclease dead mutants or the absence of Exo1, arguing that Rad53-dependent phosphorylation is the mayor requirement to preserve fork stability. We have also shown that this rescue is Bmh1–2 independent, arguing that the 14-3-3 proteins are dispensable for fork stabilization, at least when Exo1 is downregulated. Importantly, our results indicated that phosphorylation specifically inhibits the 5' to 3'exo-nuclease activity, suggesting that this activity of Exo1 and not the flap-endonuclease, is the enzymatic activity responsible of the collapse of stalled replication forks in checkpoint mutants.
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Affiliation(s)
- Esther C Morafraile
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - Alberto Bugallo
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - Raquel Carreira
- Departamento de Bioquímica y Biología Molecular, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS) - Instituto de Investigación Sanitaria (IDIS), Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - María Fernández
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | | | - Miguel G Blanco
- Departamento de Bioquímica y Biología Molecular, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS) - Instituto de Investigación Sanitaria (IDIS), Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Mónica Segurado
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain.,Departamento de Microbiología y Genética, Campus Miguel de Unamuno, Universidad de Salamanca, Salamanca 37007, Spain
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22
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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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23
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Chong SY, Cutler S, Lin JJ, Tsai CH, Tsai HK, Biggins S, Tsukiyama T, Lo YC, Kao CF. H3K4 methylation at active genes mitigates transcription-replication conflicts during replication stress. Nat Commun 2020; 11:809. [PMID: 32041946 PMCID: PMC7010754 DOI: 10.1038/s41467-020-14595-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 01/16/2020] [Indexed: 12/11/2022] Open
Abstract
Transcription-replication conflicts (TRCs) occur when intensive transcriptional activity compromises replication fork stability, potentially leading to gene mutations. Transcription-deposited H3K4 methylation (H3K4me) is associated with regions that are susceptible to TRCs; however, the interplay between H3K4me and TRCs is unknown. Here we show that H3K4me aggravates TRC-induced replication failure in checkpoint-defective cells, and the presence of methylated H3K4 slows down ongoing replication. Both S-phase checkpoint activity and H3K4me are crucial for faithful DNA synthesis under replication stress, especially in highly transcribed regions where the presence of H3K4me is highest and TRCs most often occur. H3K4me mitigates TRCs by decelerating ongoing replication, analogous to how speed bumps slow down cars. These findings establish the concept that H3K4me defines the transcriptional status of a genomic region and defends the genome from TRC-mediated replication stress and instability. Transcription-replication conflicts (TRC) can contribute to genome instability. Here the authors reveal that under replication stress H3K4 methylation can play a role in TRC prevention.
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Affiliation(s)
- Shin Yen Chong
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan.,Graduate Institute of Food Science and Technology, National Taiwan University, Taipei, 10617, Taiwan
| | - Sam Cutler
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Jing-Jer Lin
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, 10051, Taiwan
| | - Cheng-Hung Tsai
- Institute of Information Science, Academia Sinica, Nankang, Taipei, 11529, Taiwan
| | - Huai-Kuang Tsai
- Institute of Information Science, Academia Sinica, Nankang, Taipei, 11529, Taiwan
| | - Sue Biggins
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA.,Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Toshio Tsukiyama
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Yi-Chen Lo
- Graduate Institute of Food Science and Technology, National Taiwan University, Taipei, 10617, Taiwan.
| | - Cheng-Fu Kao
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan.
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24
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Achar YJ, Adhil M, Choudhary R, Gilbert N, Foiani M. Negative supercoil at gene boundaries modulates gene topology. Nature 2020; 577:701-705. [PMID: 31969709 DOI: 10.1038/s41586-020-1934-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 11/25/2019] [Indexed: 11/08/2022]
Abstract
Transcription challenges the integrity of replicating chromosomes by generating topological stress and conflicts with forks1,2. The DNA topoisomerases Top1 and Top2 and the HMGB family protein Hmo1 assist DNA replication and transcription3-6. Here we describe the topological architecture of genes in Saccharomyces cerevisiae during the G1 and S phases of the cell cycle. We found under-wound DNA at gene boundaries and over-wound DNA within coding regions. This arrangement does not depend on Pol II or S phase. Top2 and Hmo1 preserve negative supercoil at gene boundaries, while Top1 acts at coding regions. Transcription generates RNA-DNA hybrids within coding regions, independently of fork orientation. During S phase, Hmo1 protects under-wound DNA from Top2, while Top2 confines Pol II and Top1 at coding units, counteracting transcription leakage and aberrant hybrids at gene boundaries. Negative supercoil at gene boundaries prevents supercoil diffusion and nucleosome repositioning at coding regions. DNA looping occurs at Top2 clusters. We propose that Hmo1 locks gene boundaries in a cruciform conformation and, with Top2, modulates the architecture of genes that retain the memory of the topological arrangements even when transcription is repressed.
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MESH Headings
- Chromatin Assembly and Disassembly
- DNA Replication
- DNA Topoisomerases, Type I/metabolism
- DNA Topoisomerases, Type II/genetics
- DNA Topoisomerases, Type II/metabolism
- DNA, Cruciform/chemistry
- DNA, Cruciform/genetics
- DNA, Cruciform/metabolism
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- DNA, Fungal/metabolism
- DNA, Superhelical/chemistry
- DNA, Superhelical/genetics
- DNA, Superhelical/metabolism
- G1 Phase
- Gene Expression Regulation, Fungal
- Genes, Fungal
- High Mobility Group Proteins/metabolism
- Mutation
- Nucleic Acid Hybridization
- Nucleosomes/chemistry
- Nucleosomes/genetics
- Nucleosomes/metabolism
- Open Reading Frames/genetics
- RNA Polymerase II/genetics
- RNA Polymerase II/metabolism
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- S Phase
- Saccharomyces cerevisiae/cytology
- Saccharomyces cerevisiae/enzymology
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae Proteins/metabolism
- Transcription, Genetic
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Affiliation(s)
| | - Mohamood Adhil
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare), Milan, Italy
| | - Ramveer Choudhary
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare), Milan, Italy
| | - Nick Gilbert
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Marco Foiani
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare), Milan, Italy.
- Università degli Studi di Milano, Milan, Italy.
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25
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Zapatka M, Pociño-Merino I, Heluani-Gahete H, Bermúdez-López M, Tarrés M, Ibars E, Solé-Soler R, Gutiérrez-Escribano P, Apostolova S, Casas C, Aragon L, Wellinger R, Colomina N, Torres-Rosell J. Sumoylation of Smc5 Promotes Error-free Bypass at Damaged Replication Forks. Cell Rep 2019; 29:3160-3172.e4. [DOI: 10.1016/j.celrep.2019.10.123] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 09/25/2019] [Accepted: 10/29/2019] [Indexed: 12/15/2022] Open
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26
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Lanz MC, Dibitetto D, Smolka MB. DNA damage kinase signaling: checkpoint and repair at 30 years. EMBO J 2019; 38:e101801. [PMID: 31393028 PMCID: PMC6745504 DOI: 10.15252/embj.2019101801] [Citation(s) in RCA: 151] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/03/2019] [Accepted: 07/24/2019] [Indexed: 12/27/2022] Open
Abstract
From bacteria to mammalian cells, damaged DNA is sensed and targeted by DNA repair pathways. In eukaryotes, kinases play a central role in coordinating the DNA damage response. DNA damage signaling kinases were identified over two decades ago and linked to the cell cycle checkpoint concept proposed by Weinert and Hartwell in 1988. Connections between the DNA damage signaling kinases and DNA repair were scant at first, and the initial perception was that the importance of these kinases for genome integrity was largely an indirect effect of their roles in checkpoints, DNA replication, and transcription. As more substrates of DNA damage signaling kinases were identified, it became clear that they directly regulate a wide range of DNA repair factors. Here, we review our current understanding of DNA damage signaling kinases, delineating the key substrates in budding yeast and humans. We trace the progress of the field in the last 30 years and discuss our current understanding of the major substrate regulatory mechanisms involved in checkpoint responses and DNA repair.
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Affiliation(s)
- Michael Charles Lanz
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Diego Dibitetto
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Marcus Bustamante Smolka
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
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27
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Julius J, Peng J, McCulley A, Caridi C, Arnak R, See C, Nugent CI, Feng W, Bachant J. Inhibition of spindle extension through the yeast S phase checkpoint is coupled to replication fork stability and the integrity of centromeric DNA. Mol Biol Cell 2019; 30:2771-2789. [PMID: 31509480 PMCID: PMC6789157 DOI: 10.1091/mbc.e19-03-0156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Budding yeast treated with hydroxyurea (HU) activate the S phase checkpoint kinase Rad53, which prevents DNA replication forks from undergoing aberrant structural transitions and nuclease processing. Rad53 is also required to prevent premature extension of the mitotic spindle that assembles during a HU-extended S phase. Here we present evidence that checkpoint restraint of spindle extension is directly coupled to Rad53 control of replication fork stability. In budding yeast, centromeres are flanked by replication origins that fire in early S phase. Mutations affecting the Zn2+-finger of Dbf4, an origin activator, preferentially reduce centromere-proximal origin firing in HU, corresponding with suppression of rad53 spindle extension. Inactivating Exo1 nuclease or displacing centromeres from origins provides a similar suppression. Conversely, short-circuiting Rad53 targeting of Dbf4, Sld3, and Dun1, substrates contributing to fork stability, induces spindle extension. These results reveal spindle extension in HU-treated rad53 mutants is a consequence of replication fork catastrophes at centromeres. When such catastrophes occur, centromeres become susceptible to nucleases, disrupting kinetochore function and spindle force balancing mechanisms. At the same time, our data indicate centromere duplication is not required to stabilize S phase spindle structure, leading us to propose a model for how monopolar kinetochore-spindle attachments may contribute to spindle force balance in HU.
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Affiliation(s)
- Jeff Julius
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521
| | - Jie Peng
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Andrew McCulley
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Chris Caridi
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521
| | - Remigiusz Arnak
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Colby See
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521
| | - Constance I Nugent
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521
| | - Wenyi Feng
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Jeff Bachant
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521
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28
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Psakhye I, Castellucci F, Branzei D. SUMO-Chain-Regulated Proteasomal Degradation Timing Exemplified in DNA Replication Initiation. Mol Cell 2019; 76:632-645.e6. [PMID: 31519521 PMCID: PMC6891891 DOI: 10.1016/j.molcel.2019.08.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 07/01/2019] [Accepted: 08/01/2019] [Indexed: 11/18/2022]
Abstract
Similar to ubiquitin, SUMO forms chains, but the identity of SUMO-chain-modified factors and the purpose of this modification remain largely unknown. Here, we identify the budding yeast SUMO protease Ulp2, able to disassemble SUMO chains, as a DDK interactor enriched at replication origins that promotes DNA replication initiation. Replication-engaged DDK is SUMOylated on chromatin, becoming a degradation-prone substrate when Ulp2 no longer protects it against SUMO chain assembly. Specifically, SUMO chains channel DDK for SUMO-targeted ubiquitin ligase Slx5/Slx8-mediated and Cdc48 segregase-assisted proteasomal degradation. Importantly, the SUMOylation-defective ddk-KR mutant rescues inefficient replication onset and MCM activation in cells lacking Ulp2, suggesting that SUMO chains time DDK degradation. Using two unbiased proteomic approaches, we further identify subunits of the MCM helicase and other factors as SUMO-chain-modified degradation-prone substrates of Ulp2 and Slx5/Slx8. We thus propose SUMO-chain/Ulp2-protease-regulated proteasomal degradation as a mechanism that times the availability of functionally engaged SUMO-modified protein pools during replication and beyond.
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Affiliation(s)
- Ivan Psakhye
- IFOM, FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | | | - Dana Branzei
- IFOM, 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.
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29
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Saatchi F, Kirchmaier AL. Tolerance of DNA Replication Stress Is Promoted by Fumarate Through Modulation of Histone Demethylation and Enhancement of Replicative Intermediate Processing in Saccharomyces cerevisiae. Genetics 2019; 212:631-654. [PMID: 31123043 PMCID: PMC6614904 DOI: 10.1534/genetics.119.302238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 05/07/2019] [Indexed: 12/28/2022] Open
Abstract
Fumarase is a well-characterized TCA cycle enzyme that catalyzes the reversible conversion of fumarate to malate. In mammals, fumarase acts as a tumor suppressor, and loss-of-function mutations in the FH gene in hereditary leiomyomatosis and renal cell cancer result in the accumulation of intracellular fumarate-an inhibitor of α-ketoglutarate-dependent dioxygenases. Fumarase promotes DNA repair by nonhomologous end joining in mammalian cells through interaction with the histone variant H2A.Z, and inhibition of KDM2B, a H3 K36-specific histone demethylase. Here, we report that Saccharomyces cerevisiae fumarase, Fum1p, acts as a response factor during DNA replication stress, and fumarate enhances survival of yeast lacking Htz1p (H2A.Z in mammals). We observed that exposure to DNA replication stress led to upregulation as well as nuclear enrichment of Fum1p, and raising levels of fumarate in cells via deletion of FUM1 or addition of exogenous fumarate suppressed the sensitivity to DNA replication stress of htz1Δ mutants. This suppression was independent of modulating nucleotide pool levels. Rather, our results are consistent with fumarate conferring resistance to DNA replication stress in htz1Δ mutants by inhibiting the H3 K4-specific histone demethylase Jhd2p, and increasing H3 K4 methylation. Although the timing of checkpoint activation and deactivation remained largely unaffected by fumarate, sensors and mediators of the DNA replication checkpoint were required for fumarate-dependent resistance to replication stress in the htz1Δ mutants. Together, our findings imply metabolic enzymes and metabolites aid in processing replicative intermediates by affecting chromatin modification states, thereby promoting genome integrity.
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Affiliation(s)
- Faeze Saatchi
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
- Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907
| | - Ann L Kirchmaier
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
- Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907
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30
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García-Rodríguez N, Wong RP, Ulrich HD. The helicase Pif1 functions in the template switching pathway of DNA damage bypass. Nucleic Acids Res 2019; 46:8347-8356. [PMID: 30107417 PMCID: PMC6144865 DOI: 10.1093/nar/gky648] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 08/08/2018] [Indexed: 11/13/2022] Open
Abstract
Replication of damaged DNA is challenging because lesions in the replication template frequently interfere with an orderly progression of the replisome. In this situation, complete duplication of the genome is ensured by the action of DNA damage bypass pathways effecting either translesion synthesis by specialized, damage-tolerant DNA polymerases or a recombination-like mechanism called template switching (TS). Here we report that budding yeast Pif1, a helicase known to be involved in the resolution of complex DNA structures as well as the maturation of Okazaki fragments during replication, contributes to DNA damage bypass. We show that Pif1 expands regions of single-stranded DNA, so-called daughter-strand gaps, left behind the replication fork as a consequence of replisome re-priming. This function requires interaction with the replication clamp, proliferating cell nuclear antigen, facilitating its recruitment to damage sites, and complements the activity of an exonuclease, Exo1, in the processing of post-replicative daughter-strand gaps in preparation for TS. Our results thus reveal a novel function of a conserved DNA helicase that is known as a key player in genome maintenance.
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Affiliation(s)
| | - Ronald P Wong
- Institute of Molecular Biology (IMB), Ackermannweg 4, D-55128 Mainz, Germany
| | - Helle D Ulrich
- Institute of Molecular Biology (IMB), Ackermannweg 4, D-55128 Mainz, Germany
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31
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Nickens DG, Sausen CW, Bochman ML. The Biochemical Activities of the Saccharomyces cerevisiae Pif1 Helicase Are Regulated by Its N-Terminal Domain. Genes (Basel) 2019; 10:genes10060411. [PMID: 31142053 PMCID: PMC6628001 DOI: 10.3390/genes10060411] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/17/2019] [Accepted: 05/20/2019] [Indexed: 02/08/2023] Open
Abstract
: Pif1 family helicases represent a highly conserved class of enzymes involved in multiple aspects of genome maintenance. Many Pif1 helicases are multi-domain proteins, but the functions of their non-helicase domains are poorly understood. Here, we characterized how the N-terminal domain (NTD) of the Saccharomyces cerevisiae Pif1 helicase affects its functions both in vivo and in vitro. Removal of the Pif1 NTD alleviated the toxicity associated with Pif1 overexpression in yeast. Biochemically, the N-terminally truncated Pif1 (Pif1ΔN) retained in vitro DNA binding, DNA unwinding, and telomerase regulation activities, but these activities differed markedly from those displayed by full-length recombinant Pif1. However, Pif1ΔN was still able to synergize with the Hrq1 helicase to inhibit telomerase activity in vitro, similar to full-length Pif1. These data impact our understanding of Pif1 helicase evolution and the roles of these enzymes in the maintenance of genome integrity.
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Affiliation(s)
- David G Nickens
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA.
| | - Christopher W Sausen
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA.
| | - Matthew L Bochman
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA.
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32
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Kim SM, Forsburg SL. Regulation of Structure-Specific Endonucleases in Replication Stress. Genes (Basel) 2018; 9:genes9120634. [PMID: 30558228 PMCID: PMC6316474 DOI: 10.3390/genes9120634] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 12/16/2022] Open
Abstract
Replication stress results in various forms of aberrant replication intermediates that need to be resolved for faithful chromosome segregation. Structure-specific endonucleases (SSEs) recognize DNA secondary structures rather than primary sequences and play key roles during DNA repair and replication stress. Holliday junction resolvase MUS81 (methyl methane sulfonate (MMS), and UV-sensitive protein 81) and XPF (xeroderma pigmentosum group F-complementing protein) are a subset of SSEs that resolve aberrant replication structures. To ensure genome stability and prevent unnecessary DNA breakage, these SSEs are tightly regulated by the cell cycle and replication checkpoints. We discuss the regulatory network that control activities of MUS81 and XPF and briefly mention other SSEs involved in the resolution of replication intermediates.
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Affiliation(s)
- Seong Min Kim
- Program in Molecular & Computational Biology, University of Southern California, Los Angeles, CA 90089, USA.
| | - Susan L Forsburg
- Program in Molecular & Computational Biology, University of Southern California, Los Angeles, CA 90089, USA.
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33
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Rossi SE, Foiani M, Giannattasio M. Dna2 processes behind the fork long ssDNA flaps generated by Pif1 and replication-dependent strand displacement. Nat Commun 2018; 9:4830. [PMID: 30446656 PMCID: PMC6240037 DOI: 10.1038/s41467-018-07378-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 10/16/2018] [Indexed: 01/09/2023] Open
Abstract
Dna2 is a DNA helicase-endonuclease mediating DSB resection and Okazaki fragment processing. Dna2 ablation is lethal and rescued by inactivation of Pif1, a helicase assisting Okazaki fragment maturation, Pol32, a DNA polymerase δ subunit, and Rad9, a DNA damage response (DDR) factor. Dna2 counteracts fork reversal and promotes fork restart. Here we show that Dna2 depletion generates lethal DNA structures activating the DDR. While PIF1 deletion rescues the lethality of Dna2 depletion, RAD9 ablation relieves the first cell cycle arrest causing genotoxicity after few cell divisions. Slow fork speed attenuates DDR in Dna2 deprived cells. Electron microscopy shows that Dna2-ablated cells accumulate long ssDNA flaps behind the forks through Pif1 and fork speed. We suggest that Dna2 offsets the strand displacement activity mediated by the lagging strand polymerase and Pif1, processing long ssDNA flaps to prevent DDR activation. We propose that this Dna2 function has been hijacked by Break Induced Replication in DSB processing. DNA2 encodes a 5′ flap DNA endonuclease involved in replication and DNA double strand break processing. Here the authors by using a conditional degron system together with electron microscopy characterize the role played by Dna2 and Pif1 helicase during unperturbed DNA replication in S. cerevisiae.
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Affiliation(s)
- Silvia Emma Rossi
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare), Via Adamello 16, Milan, 20139, Italy
| | - Marco Foiani
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare), Via Adamello 16, Milan, 20139, Italy. .,Dipartimento di Oncologia ed Emato-Oncologia, Universita' degli Studi di Milano, Via Festa del Perdono 7, Milan, 20122, Italy.
| | - Michele Giannattasio
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare), Via Adamello 16, Milan, 20139, Italy. .,Dipartimento di Oncologia ed Emato-Oncologia, Universita' degli Studi di Milano, Via Festa del Perdono 7, Milan, 20122, Italy.
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34
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Villa-Hernández S, Bermejo R. Cohesin dynamic association to chromatin and interfacing with replication forks in genome integrity maintenance. Curr Genet 2018; 64:1005-1013. [PMID: 29549581 DOI: 10.1007/s00294-018-0824-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 03/12/2018] [Accepted: 03/13/2018] [Indexed: 01/09/2023]
Abstract
Proliferating cells need to accurately duplicate and pass their genetic material on to daughter cells. Problems during replication and partition challenge the structural and numerical integrity of chromosomes. Diverse mechanisms, as the DNA replication checkpoint, survey the correct progression of replication and couple it with other cell cycle events to preserve genome integrity. The structural maintenance of chromosomes (SMC) cohesin complex primarily contributes to chromosome duplication by mediating the tethering of newly replicated sister chromatids, thus assisting their equal segregation in mitosis. In addition, cohesin exerts important functions in genome organization, gene expression and DNA repair. These are determined by cohesin's ability to bring together different DNA segments and, hence, by the fashion and dynamics of its interaction with chromatin. It recently emerged that cohesin contributes to the protection of stalled replication forks through a mechanism requiring its timely mobilization from unreplicated DNA and relocation to nascent strands. This mechanism relies on DNA replication checkpoint-dependent cohesin ubiquitylation and promotes nascent sister chromatid entrapment, likely contributing to preserve stalled replisome-fork architectural integrity. Here we review how cohesin dynamic association to chromatin is controlled through post-translational modifications to dictate its functions during chromosome duplication. We also discuss recent insights on the mechanism that mediates interfacing of replisome components with chromatin-bound cohesin and its contribution to the establishment of sister chromatid cohesion and the protection of stalled replication forks.
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Affiliation(s)
- Sara Villa-Hernández
- Centro de Investigaciones Biológicas (CIB-CSIC), Calle Ramiro de Maeztu 9, 28040, Madrid, Spain
- Wolfson Centre for Age-Related Diseases, King's College London, London, SE1 1UL, UK
| | - Rodrigo Bermejo
- Centro de Investigaciones Biológicas (CIB-CSIC), Calle Ramiro de Maeztu 9, 28040, Madrid, Spain.
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35
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Srivatsan A, Li BZ, Szakal B, Branzei D, Putnam CD, Kolodner RD. The Swr1 chromatin-remodeling complex prevents genome instability induced by replication fork progression defects. Nat Commun 2018; 9:3680. [PMID: 30206225 PMCID: PMC6134005 DOI: 10.1038/s41467-018-06131-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 08/09/2018] [Indexed: 01/05/2023] Open
Abstract
Genome instability is associated with tumorigenesis. Here, we identify a role for the histone Htz1, which is deposited by the Swr1 chromatin-remodeling complex (SWR-C), in preventing genome instability in the absence of the replication fork/replication checkpoint proteins Mrc1, Csm3, or Tof1. When combined with deletion of SWR1 or HTZ1, deletion of MRC1, CSM3, or TOF1 or a replication-defective mrc1 mutation causes synergistic increases in gross chromosomal rearrangement (GCR) rates, accumulation of a broad spectrum of GCRs, and hypersensitivity to replication stress. The double mutants have severe replication defects and accumulate aberrant replication intermediates. None of the individual mutations cause large increases in GCR rates; however, defects in MRC1, CSM3 or TOF1 cause activation of the DNA damage checkpoint and replication defects. We propose a model in which Htz1 deposition and retention in chromatin prevents transiently stalled replication forks that occur in mrc1, tof1, or csm3 mutants from being converted to DNA double-strand breaks that trigger genome instability.
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Affiliation(s)
- Anjana Srivatsan
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0669, USA
| | - Bin-Zhong Li
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0669, USA
| | - Barnabas Szakal
- The FIRC Institute of Molecular Oncology Foundation, Via Adamello 16, 20139, Milan, Italy
| | - Dana Branzei
- The FIRC Institute of Molecular Oncology Foundation, Via Adamello 16, 20139, Milan, Italy.,Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Via Abbiategrasso 207, 27100, Pavia, Italy
| | - Christopher D Putnam
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0669, USA.,Departments of Medicine, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0669, USA
| | - Richard D Kolodner
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0669, USA. .,Cellular and Molecular Medicine, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0669, USA. .,Moores-UCSD Cancer Center, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0669, USA. .,Institute of Genomic Medicine, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0669, USA.
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36
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García-Rodríguez N, Morawska M, Wong RP, Daigaku Y, Ulrich HD. Spatial separation between replisome- and template-induced replication stress signaling. EMBO J 2018; 37:embj.201798369. [PMID: 29581097 PMCID: PMC5920239 DOI: 10.15252/embj.201798369] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 01/29/2018] [Accepted: 02/26/2018] [Indexed: 11/09/2022] Open
Abstract
Polymerase‐blocking DNA lesions are thought to elicit a checkpoint response via accumulation of single‐stranded DNA at stalled replication forks. However, as an alternative to persistent fork stalling, re‐priming downstream of lesions can give rise to daughter‐strand gaps behind replication forks. We show here that the processing of such structures by an exonuclease, Exo1, is required for timely checkpoint activation, which in turn prevents further gap erosion in S phase. This Rad9‐dependent mechanism of damage signaling is distinct from the Mrc1‐dependent, fork‐associated response to replication stress induced by conditions such as nucleotide depletion or replisome‐inherent problems, but reminiscent of replication‐independent checkpoint activation by single‐stranded DNA. Our results indicate that while replisome stalling triggers a checkpoint response directly at the stalled replication fork, the response to replication stress elicited by polymerase‐blocking lesions mainly emanates from Exo1‐processed, postreplicative daughter‐strand gaps, thus offering a mechanistic explanation for the dichotomy between replisome‐ versus template‐induced checkpoint signaling.
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Affiliation(s)
| | - Magdalena Morawska
- Institute of Molecular Biology (IMB), Mainz, Germany.,Cancer Research UK London Research Institute, Clare Hall Laboratories, Blanche Lane South Mimms, UK
| | - Ronald P Wong
- Institute of Molecular Biology (IMB), Mainz, Germany
| | - Yasukazu Daigaku
- Cancer Research UK London Research Institute, Clare Hall Laboratories, Blanche Lane South Mimms, UK
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37
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Structure and function of Pif1 helicase. Biochem Soc Trans 2017; 45:1159-1171. [PMID: 28900015 DOI: 10.1042/bst20170096] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 08/10/2017] [Accepted: 08/11/2017] [Indexed: 12/18/2022]
Abstract
Pif1 family helicases have multiple roles in the maintenance of nuclear and mitochondrial DNA in eukaryotes. Saccharomyces cerevisiae Pif1 is involved in replication through barriers to replication, such as G-quadruplexes and protein blocks, and reduces genetic instability at these sites. Another Pif1 family helicase in S. cerevisiae, Rrm3, assists in fork progression through replication fork barriers at the rDNA locus and tRNA genes. ScPif1 (Saccharomyces cerevisiae Pif1) also negatively regulates telomerase, facilitates Okazaki fragment processing, and acts with polymerase δ in break-induced repair. Recent crystal structures of bacterial Pif1 helicases and the helicase domain of human PIF1 combined with several biochemical and biological studies on the activities of Pif1 helicases have increased our understanding of the function of these proteins. This review article focuses on these structures and the mechanism(s) proposed for Pif1's various activities on DNA.
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38
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Abstract
One major challenge during genome duplication is the stalling of DNA replication forks by various forms of template blockages. As these barriers can lead to incomplete replication, multiple mechanisms have to act concertedly to correct and rescue stalled replication forks. Among these mechanisms, replication fork regression entails simultaneous annealing of nascent and template strands, which leads to regression of replication forks and formation of four-way DNA junctions. In principle, this process can lead to either positive outcomes, such as DNA repair and replication resumption, or less desirable outcomes, such as misalignment between nascent and template DNA and DNA cleavage. While our understanding of replication fork regression and its various possible outcomes is still at an early stage, recent studies using combinational approaches in multiple organisms have begun to identify the enzymes that catalyze this DNA transaction and how these enzymes are regulated, as well as the specific manners by which fork regression can influence replication. This review summarizes these recent progresses. In keeping with the theme of this series of reviews, we focus on studies in yeast and compare to findings in higher eukaryotes. It is anticipated that these findings will form the basis for future endeavors to further elucidate replication fork remodeling and its implications for genome maintenance.
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39
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Ferrari E, Bruhn C, Peretti M, Cassani C, Carotenuto WV, Elgendy M, Shubassi G, Lucca C, Bermejo R, Varasi M, Minucci S, Longhese MP, Foiani M. PP2A Controls Genome Integrity by Integrating Nutrient-Sensing and Metabolic Pathways with the DNA Damage Response. Mol Cell 2017. [PMID: 28648781 PMCID: PMC5526790 DOI: 10.1016/j.molcel.2017.05.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mec1ATR mediates the DNA damage response (DDR), integrating chromosomal signals and mechanical stimuli. We show that the PP2A phosphatases, ceramide-activated enzymes, couple cell metabolism with the DDR. Using genomic screens, metabolic analysis, and genetic and pharmacological studies, we found that PP2A attenuates the DDR and that three metabolic circuits influence the DDR by modulating PP2A activity. Irc21, a putative cytochrome b5 reductase that promotes the condensation reaction generating dihydroceramides (DHCs), and Ppm1, a PP2A methyltransferase, counteract the DDR by activating PP2A; conversely, the nutrient-sensing TORC1-Tap42 axis sustains DDR activation by inhibiting PP2A. Loss-of-function mutations in IRC21, PPM1, and PP2A and hyperactive tap42 alleles rescue mec1 mutants. Ceramides synergize with rapamycin, a TORC1 inhibitor, in counteracting the DDR. Hence, PP2A integrates nutrient-sensing and metabolic pathways to attenuate the Mec1ATR response. Our observations imply that metabolic changes affect genome integrity and may help with exploiting therapeutic options and repositioning known drugs.
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Affiliation(s)
- Elisa Ferrari
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Christopher Bruhn
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Marta Peretti
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Corinne Cassani
- Università degli Studi di Milano-Bicocca, 20126 Milan, Italy
| | | | - Mohamed Elgendy
- Istituto Europeo di Oncologia, Via Adamello 16, 20139 Milan, Italy
| | - Ghadeer Shubassi
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Chiara Lucca
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Rodrigo Bermejo
- Centro de Investigaciones Biológicas (CIB-CSIC), 28040 Madrid, Spain
| | - Mario Varasi
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Saverio Minucci
- Istituto Europeo di Oncologia, Via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, 20133 Milan, Italy
| | | | - Marco Foiani
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, 20133 Milan, Italy.
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40
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Muñoz-Galván S, García-Rubio M, Ortega P, Ruiz JF, Jimeno S, Pardo B, Gómez-González B, Aguilera A. A new role for Rrm3 in repair of replication-born DNA breakage by sister chromatid recombination. PLoS Genet 2017; 13:e1006781. [PMID: 28475600 PMCID: PMC5438189 DOI: 10.1371/journal.pgen.1006781] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 05/19/2017] [Accepted: 04/26/2017] [Indexed: 11/19/2022] Open
Abstract
Replication forks stall at different DNA obstacles such as those originated by transcription. Fork stalling can lead to DNA double-strand breaks (DSBs) that will be preferentially repaired by homologous recombination when the sister chromatid is available. The Rrm3 helicase is a replisome component that promotes replication upon fork stalling, accumulates at highly transcribed regions and prevents not only transcription-induced replication fork stalling but also transcription-associated hyper-recombination. This led us to explore the possible role of Rrm3 in the repair of DSBs when originating at the passage of the replication fork. Using a mini-HO system that induces mainly single-stranded DNA breaks, we show that rrm3Δ cells are defective in DSB repair. The defect is clearly seen in sister chromatid recombination, the major repair pathway of replication-born DSBs. Our results indicate that Rrm3 recruitment to replication-born DSBs is crucial for viability, uncovering a new role for Rrm3 in the repair of broken replication forks. DNA replication needs to be precise to ensure cell survival and to avoid genetic instability. Different DNA obstacles, such as those originated by transcription, frequently hamper replication fork progression leading to fork stalling or even fork breakage. This requires the homologous recombination machinery to repair the damage. Here, we uncovered a role for yeast Rrm3, a replisome component known to promote replication upon fork stalling, in the repair of replication-born double strand breaks. In particular, rrm3Δ cells show a defect in the recombination with the sister chromatid, the preferred template for the maintenance of genome integrity. Our results support the possibility that the known accumulation of Rrm3 at sites of active transcription reflects an active role of Rrm3 in the repair of broken forks.
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Affiliation(s)
- Sandra Muñoz-Galván
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - María García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Pedro Ortega
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Jose F. Ruiz
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Sonia Jimeno
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Benjamin Pardo
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
- * E-mail: (AA); (BGG)
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
- * E-mail: (AA); (BGG)
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Branzei D, Szakal B. Building up and breaking down: mechanisms controlling recombination during replication. Crit Rev Biochem Mol Biol 2017; 52:381-394. [PMID: 28325102 DOI: 10.1080/10409238.2017.1304355] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The complete and faithful duplication of the genome is an essential prerequisite for proliferating cells to maintain genome integrity. This objective is greatly challenged by DNA damage encountered during replication, which causes fork stalling and in certain cases, fork breakage. DNA damage tolerance (DDT) pathways mitigate the effects on fork stability induced by replication fork stalling by mediating damage-bypass and replication fork restart. These DDT mechanisms, largely relying on homologous recombination (HR) and specialized polymerases, can however contribute to genome rearrangements and mutagenesis. There is a profound connection between replication and recombination: recombination proteins protect replication forks from nuclease-mediated degradation of the nascent DNA strands and facilitate replication completion in cells challenged by DNA damage. Moreover, in case of fork collapse and formation of double strand breaks (DSBs), the recombination factors present or recruited to the fork facilitate HR-mediated DSB repair, which is primarily error-free. Disruption of HR is inexorably linked to genome instability, but the premature activation of HR during replication often leads to genome rearrangements. Faithful replication necessitates the downregulation of HR and disruption of active RAD51 filaments at replication forks, but upon persistent fork stalling, building up of HR is critical for the reorganization of the replication fork and for filling-in of the gaps associated with discontinuous replication induced by DNA lesions. Here we summarize and reflect on our understanding of the mechanisms that either suppress recombination or locally enhance it during replication, and the principles that underlie this regulation.
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Affiliation(s)
- Dana Branzei
- a IFOM, the FIRC Institute of Molecular Oncology , Milan , Italy
| | - Barnabas Szakal
- a IFOM, the FIRC Institute of Molecular Oncology , Milan , Italy
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S-phase checkpoint regulations that preserve replication and chromosome integrity upon dNTP depletion. Cell Mol Life Sci 2017; 74:2361-2380. [PMID: 28220209 PMCID: PMC5487892 DOI: 10.1007/s00018-017-2474-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 12/29/2016] [Accepted: 01/23/2017] [Indexed: 11/18/2022]
Abstract
DNA replication stress, an important source of genomic instability, arises upon different types of DNA replication perturbations, including those that stall replication fork progression. Inhibitors of the cellular pool of deoxynucleotide triphosphates (dNTPs) slow down DNA synthesis throughout the genome. Following depletion of dNTPs, the highly conserved replication checkpoint kinase pathway, also known as the S-phase checkpoint, preserves the functionality and structure of stalled DNA replication forks and prevents chromosome fragmentation. The underlying mechanisms involve pathways extrinsic to replication forks, such as those involving regulation of the ribonucleotide reductase activity, the temporal program of origin firing, and cell cycle transitions. In addition, the S-phase checkpoint modulates the function of replisome components to promote replication integrity. This review summarizes the various functions of the replication checkpoint in promoting replication fork stability and genome integrity in the face of replication stress caused by dNTP depletion.
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43
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Abstract
DNA topological transitions occur when replication forks encounter other DNA transactions such as transcription. Failure in resolving such conflicts leads to generation of aberrant replication and transcription intermediates that might have adverse effects on genome stability. Cells have evolved numerous surveillance mechanisms to avoid, tolerate, and resolve such replication-transcription conflicts. Defects or non-coordination in such cellular mechanisms might have catastrophic effect on cell viability. In this chapter, we review consequences of replication encounters with transcription and its associated events, topological challenges, and how these inevitable conflicts alter the genome structure and functions.
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Mec1/ATR, the Program Manager of Nucleic Acids Inc. Genes (Basel) 2016; 8:genes8010010. [PMID: 28036033 PMCID: PMC5295005 DOI: 10.3390/genes8010010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 12/19/2016] [Accepted: 12/22/2016] [Indexed: 11/17/2022] Open
Abstract
Eukaryotic cells are equipped with surveillance mechanisms called checkpoints to ensure proper execution of cell cycle events. Among these are the checkpoints that detect DNA damage or replication perturbations and coordinate cellular activities to maintain genome stability. At the forefront of damage sensing is an evolutionarily conserved molecule, known respectively in budding yeast and humans as Mec1 (Mitosis entry checkpoint 1) and ATR (Ataxia telangiectasia and Rad3-related protein). Through phosphorylation, Mec1/ATR activates downstream components of a signaling cascade to maintain nucleotide pool balance, protect replication fork integrity, regulate activation of origins of replication, coordinate DNA repair, and implement cell cycle delay. This list of functions continues to expand as studies have revealed that Mec1/ATR modularly interacts with various protein molecules in response to different cellular cues. Among these newly assigned functions is the regulation of RNA metabolism during checkpoint activation and the coordination of replication-transcription conflicts. In this review, I will highlight some of these new functions of Mec1/ATR with a focus on the yeast model organism.
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Syed S, Desler C, Rasmussen LJ, Schmidt KH. A Novel Rrm3 Function in Restricting DNA Replication via an Orc5-Binding Domain Is Genetically Separable from Rrm3 Function as an ATPase/Helicase in Facilitating Fork Progression. PLoS Genet 2016; 12:e1006451. [PMID: 27923055 PMCID: PMC5140057 DOI: 10.1371/journal.pgen.1006451] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 10/31/2016] [Indexed: 11/21/2022] Open
Abstract
In response to replication stress cells activate the intra-S checkpoint, induce DNA repair pathways, increase nucleotide levels, and inhibit origin firing. Here, we report that Rrm3 associates with a subset of replication origins and controls DNA synthesis during replication stress. The N-terminal domain required for control of DNA synthesis maps to residues 186–212 that are also critical for binding Orc5 of the origin recognition complex. Deletion of this domain is lethal to cells lacking the replication checkpoint mediator Mrc1 and leads to mutations upon exposure to the replication stressor hydroxyurea. This novel Rrm3 function is independent of its established role as an ATPase/helicase in facilitating replication fork progression through polymerase blocking obstacles. Using quantitative mass spectrometry and genetic analyses, we find that the homologous recombination factor Rdh54 and Rad5-dependent error-free DNA damage bypass act as independent mechanisms on DNA lesions that arise when Rrm3 catalytic activity is disrupted whereas these mechanisms are dispensable for DNA damage tolerance when the replication function is disrupted, indicating that the DNA lesions generated by the loss of each Rrm3 function are distinct. Although both lesion types activate the DNA-damage checkpoint, we find that the resultant increase in nucleotide levels is not sufficient for continued DNA synthesis under replication stress. Together, our findings suggest a role of Rrm3, via its Orc5-binding domain, in restricting DNA synthesis that is genetically and physically separable from its established catalytic role in facilitating fork progression through replication blocks. When cells duplicate their genome, the replication machinery is constantly at risk of encountering obstacles, including unusual DNA structures, bound proteins, or transcribing polymerases and transcripts. Cells possess DNA helicases that facilitate movement of the replication fork through such obstacles. Here, we report the discovery that one of these DNA helicases, Rrm3, is also required for restricting DNA synthesis under replication stress. We find that the site in Rrm3 critical for this new replication function is also required for binding a subunit of the replication origin recognition complex, which raises the possibility that Rrm3 controls replication by affecting initiation. This is supported by our finding that Rrm3 associates with a subset of replication origins. Rrm3’s ability to restrict replication does not require its helicase activity or the phosphorylation site that regulates this activity. Notably, cells need error-free bypass pathways and homologous recombination to deal with DNA lesions that arise when the helicase function of Rrm3 is disrupted, but not when its replication function is disrupted. This indicates that the DNA lesions that form in the absence of the two distinct Rrm3 function are different, although both activate the DNA-damage checkpoint and are toxic to cells that lack the mediator of the replication checkpoint Mrc1.
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Affiliation(s)
- Salahuddin Syed
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, Florida, United States of America
- Graduate Program in Cellular and Molecular Biology, University of South Florida, Tampa, Florida, United States of America
| | - Claus Desler
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Lene J. Rasmussen
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Kristina H. Schmidt
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, Florida, United States of America
- Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
- * E-mail:
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Colosio A, Frattini C, Pellicanò G, Villa-Hernández S, Bermejo R. Nucleolytic processing of aberrant replication intermediates by an Exo1-Dna2-Sae2 axis counteracts fork collapse-driven chromosome instability. Nucleic Acids Res 2016; 44:10676-10690. [PMID: 27672038 PMCID: PMC5159547 DOI: 10.1093/nar/gkw858] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 09/14/2016] [Accepted: 09/17/2016] [Indexed: 12/16/2022] Open
Abstract
Problems during DNA replication underlie genomic instability and drive malignant transformation. The DNA damage checkpoint stabilizes stalled replication forks thus counteracting aberrant fork transitions, DNA breaks and chromosomal rearrangements. We analyzed fork processing in checkpoint deficient cells by coupling psoralen crosslinking with replication intermediate two-dimensional gel analysis. This revealed a novel role for Exo1 nuclease in resecting reversed replication fork structures and counteracting the accumulation of aberrant intermediates resembling fork cleavage products. Genetic analyses demonstrated a functional interplay of Exo1 with Mus81, Dna2 and Sae2 nucleases in promoting cell survival following replication stress, suggestive of concerted nucleolytic processing of stalled forks. While Mus81 and other Structure Specific Endonucleases do not contribute to obvious collapsed fork transitions, Dna2 promotes reversed fork resection likely by facilitating Exo1 access to nascent strands. Instead, Sae2 cooperates with Exo1 in counteracting putative fork cleavage events linked to double strand breaks formation and increased gross chromosomal rearrangement rates. Our data indicate that in checkpoint deficient cells diverse nuclease activities interface to eliminate aberrant replication intermediates and prevent chromosome instability.
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Affiliation(s)
- Arianna Colosio
- The F.I.R.C. Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Camilla Frattini
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Calle Zacarías González 2, 37007 Salamanca, Spain
| | - Grazia Pellicanò
- Centro de Investigaciones Biológicas (CIB-CSIC), Calle Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Sara Villa-Hernández
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Calle Zacarías González 2, 37007 Salamanca, Spain.,Centro de Investigaciones Biológicas (CIB-CSIC), Calle Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Rodrigo Bermejo
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Calle Zacarías González 2, 37007 Salamanca, Spain .,Centro de Investigaciones Biológicas (CIB-CSIC), Calle Ramiro de Maeztu 9, 28040 Madrid, Spain
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McDonald KR, Guise AJ, Pourbozorgi-Langroudi P, Cristea IM, Zakian VA, Capra JA, Sabouri N. Pfh1 Is an Accessory Replicative Helicase that Interacts with the Replisome to Facilitate Fork Progression and Preserve Genome Integrity. PLoS Genet 2016; 12:e1006238. [PMID: 27611590 PMCID: PMC5017727 DOI: 10.1371/journal.pgen.1006238] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 08/11/2016] [Indexed: 12/27/2022] Open
Abstract
Replicative DNA helicases expose the two strands of the double helix to the replication apparatus, but accessory helicases are often needed to help forks move past naturally occurring hard-to-replicate sites, such as tightly bound proteins, RNA/DNA hybrids, and DNA secondary structures. Although the Schizosaccharomyces pombe 5’-to-3’ DNA helicase Pfh1 is known to promote fork progression, its genomic targets, dynamics, and mechanisms of action are largely unknown. Here we address these questions by integrating genome-wide identification of Pfh1 binding sites, comprehensive analysis of the effects of Pfh1 depletion on replication and DNA damage, and proteomic analysis of Pfh1 interaction partners by immunoaffinity purification mass spectrometry. Of the 621 high confidence Pfh1-binding sites in wild type cells, about 40% were sites of fork slowing (as marked by high DNA polymerase occupancy) and/or DNA damage (as marked by high levels of phosphorylated H2A). The replication and integrity of tRNA and 5S rRNA genes, highly transcribed RNA polymerase II genes, and nucleosome depleted regions were particularly Pfh1-dependent. The association of Pfh1 with genomic integrity at highly transcribed genes was S phase dependent, and thus unlikely to be an artifact of high transcription rates. Although Pfh1 affected replication and suppressed DNA damage at discrete sites throughout the genome, Pfh1 and the replicative DNA polymerase bound to similar extents to both Pfh1-dependent and independent sites, suggesting that Pfh1 is proximal to the replication machinery during S phase. Consistent with this interpretation, Pfh1 co-purified with many key replisome components, including the hexameric MCM helicase, replicative DNA polymerases, RPA, and the processivity clamp PCNA in an S phase dependent manner. Thus, we conclude that Pfh1 is an accessory DNA helicase that interacts with the replisome and promotes replication and suppresses DNA damage at hard-to-replicate sites. These data provide insight into mechanisms by which this evolutionarily conserved helicase helps preserve genome integrity. Progression of the DNA replication machinery is challenged in every S phase by active transcription, tightly bound protein complexes, and formation of stable DNA secondary structures. Using genome-wide analyses, we show that the evolutionarily conserved fission yeast Pfh1 DNA helicase promotes fork progression and suppresses DNA damage at natural sites of fork pausing, which occur at “hard-to-replicate” sites. Our data suggest that Pfh1 interacts with the replication apparatus. First, mass spectrometry revealed that Pfh1 interacts with many components of the replication machinery. Second, Pfh1 and the leading strand DNA polymerase occupy many common regions genome-wide, not only hard-to-replicate sites, but also sites whose replication is not Pfh1-dependent. The human genome encodes a Pfh1 homolog, hPIF1, and contains all of the same hard-to-replicate features that make fission yeast DNA replication dependent upon Pfh1. Thus, human cells likely also require replicative accessory DNA helicases to facilitate replication at hard-to-replicate sites, and hPIF1 is a good candidate for this role.
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Affiliation(s)
- Karin R. McDonald
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Amanda J. Guise
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | | | - Ileana M. Cristea
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Virginia A. Zakian
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - John A. Capra
- Department of Biological Sciences, Vanderbilt Genetics Institute, and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail: (JAC); (NS)
| | - Nasim Sabouri
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- * E-mail: (JAC); (NS)
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Replication-Associated Recombinational Repair: Lessons from Budding Yeast. Genes (Basel) 2016; 7:genes7080048. [PMID: 27548223 PMCID: PMC4999836 DOI: 10.3390/genes7080048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 08/05/2016] [Accepted: 08/09/2016] [Indexed: 12/23/2022] Open
Abstract
Recombinational repair processes multiple types of DNA lesions. Though best understood in the repair of DNA breaks, recombinational repair is intimately linked to other situations encountered during replication. As DNA strands are decorated with many types of blocks that impede the replication machinery, a great number of genomic regions cannot be duplicated without the help of recombinational repair. This replication-associated recombinational repair employs both the core recombination proteins used for DNA break repair and the specialized factors that couple replication with repair. Studies from multiple organisms have provided insights into the roles of these specialized factors, with the findings in budding yeast being advanced through use of powerful genetics and methods for detecting DNA replication and repair intermediates. In this review, we summarize recent progress made in this organism, ranging from our understanding of the classical template switch mechanisms to gap filling and replication fork regression pathways. As many of the protein factors and biological principles uncovered in budding yeast are conserved in higher eukaryotes, these findings are crucial for stimulating studies in more complex organisms.
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García-Muse T, Aguilera A. Transcription–replication conflicts: how they occur and how they are resolved. Nat Rev Mol Cell Biol 2016; 17:553-63. [DOI: 10.1038/nrm.2016.88] [Citation(s) in RCA: 238] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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50
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Rossi SE, Carotenuto W, Giannattasio M. Genome-wide localization of Rrm3 and Pif1 DNA helicases at stalled active and inactive DNA replication forks of Saccharomyces cerevisiae. GENOMICS DATA 2015; 7:162-5. [PMID: 26981397 PMCID: PMC4778647 DOI: 10.1016/j.gdata.2015.11.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 11/30/2015] [Indexed: 10/25/2022]
Abstract
The genome of the budding yeast Saccharomyces cerevisiae is sequenced and the location and dynamic of activation of DNA replication origins are known. G1 synchronized yeast cells can be released into S-phase in the presence of hydroxyurea (HU) (1), which slows down DNA replication and retains replication forks in proximity of DNA replication origins. In this condition, the Chromatin Immuno-Precipitation on chip (ChIP on chip) (2-4) of replisome components allows the precise localization of all active DNA replication forks. This analysis can be coupled with the ssDNA-BromodeoxyUridine (ssDNA-BrdU) Immuno-Precipitation on chip (ssDNA-BrdU IP on chip) technique (5-7), which detects the location of newly synthesized DNA. Comparison of binding and BrdU incorporation profiles allows to locate a factor of interest at DNA replication forks genome wide. We present datasets deposited in the gene expression omnibus (GEO) database under accession number GSE68214, which show how the DNA helicases Rrm3 and Pif1 (8) associate to active and inactive DNA replication forks.
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Affiliation(s)
- Silvia Emma Rossi
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare) via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, Dipartimento di Bioscienze, Via Celoria 26, 20133 Milan, Italy
| | - Walter Carotenuto
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare) via Adamello 16, 20139 Milan, Italy
| | - Michele Giannattasio
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare) via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, Dipartimento di Bioscienze, Via Celoria 26, 20133 Milan, Italy
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