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Xie B, Sanford EJ, Hung SH, Wagner M, Heyer WD, Smolka MB. Multi-step control of homologous recombination via Mec1/ATR suppresses chromosomal rearrangements. EMBO J 2024; 43:3027-3043. [PMID: 38839993 PMCID: PMC11251156 DOI: 10.1038/s44318-024-00139-9] [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: 12/04/2023] [Revised: 05/19/2024] [Accepted: 05/22/2024] [Indexed: 06/07/2024] Open
Abstract
The Mec1/ATR kinase is crucial for genome stability, yet the mechanism by which it prevents gross chromosomal rearrangements (GCRs) remains unknown. Here we find that in cells with deficient Mec1 signaling, GCRs accumulate due to the deregulation of multiple steps in homologous recombination (HR). Mec1 primarily suppresses GCRs through its role in activating the canonical checkpoint kinase Rad53, which ensures the proper control of DNA end resection. Upon loss of Rad53 signaling and resection control, Mec1 becomes hyperactivated and triggers a salvage pathway in which the Sgs1 helicase is recruited to sites of DNA lesions via the 911-Dpb11 scaffolds and phosphorylated by Mec1 to favor heteroduplex rejection and limit HR-driven GCR accumulation. Fusing an ssDNA recognition domain to Sgs1 bypasses the requirement of Mec1 signaling for GCR suppression and nearly eliminates D-loop formation, thus preventing non-allelic recombination events. We propose that Mec1 regulates multiple steps of HR to prevent GCRs while ensuring balanced HR usage when needed for promoting tolerance to replication stress.
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Affiliation(s)
- Bokun Xie
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Ethan James Sanford
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Shih-Hsun Hung
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, USA
| | - Mateusz Wagner
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, USA
| | - Marcus B Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA.
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Xie B, Sanford EJ, Hung SH, Wagner MM, Heyer WD, Smolka MB. Multi-Step Control of Homologous Recombination by Mec1/ATR Ensures Robust Suppression of Gross Chromosomal Rearrangements. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.21.568146. [PMID: 38045423 PMCID: PMC10690203 DOI: 10.1101/2023.11.21.568146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
The Mec1/ATR kinase is crucial for genome stability, yet the mechanism by which it prevents gross chromosomal rearrangements (GCRs) remains unknown. Here we find that in cells with deficient Mec1 signaling, GCRs accumulate due to the deregulation of multiple steps in homologous recombination (HR). Mec1 primarily suppresses GCRs through its role in activating the canonical checkpoint kinase Rad53, which ensures the proper control of DNA end resection. Upon loss of Rad53 signaling and resection control, Mec1 becomes hyperactivated and triggers a salvage pathway in which the Sgs1 helicase is recruited to sites of DNA lesions via the 911-Dpb11 scaffolds to favor heteroduplex rejection and limit HR-driven GCR accumulation. Fusing an ssDNA recognition domain to Sgs1 bypasses the requirement of Mec1 signaling for GCR suppression and nearly eliminates D-loop formation, thus preventing non-allelic recombination events. We propose that Mec1 regulates multiple steps of HR to prevent GCRs while ensuring balanced HR usage when needed for promoting tolerance to replication stress.
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Affiliation(s)
- Bokun Xie
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Ethan James Sanford
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Shih-Hsun Hung
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, USA
| | - Mateusz Maciej Wagner
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, USA
| | - Marcus B. Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
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Gupta SV, Schmidt KH. Maintenance of Yeast Genome Integrity by RecQ Family DNA Helicases. Genes (Basel) 2020; 11:E205. [PMID: 32085395 PMCID: PMC7074392 DOI: 10.3390/genes11020205] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/11/2020] [Accepted: 02/14/2020] [Indexed: 12/28/2022] Open
Abstract
With roles in DNA repair, recombination, replication and transcription, members of the RecQ DNA helicase family maintain genome integrity from bacteria to mammals. Mutations in human RecQ helicases BLM, WRN and RecQL4 cause incurable disorders characterized by genome instability, increased cancer predisposition and premature adult-onset aging. Yeast cells lacking the RecQ helicase Sgs1 share many of the cellular defects of human cells lacking BLM, including hypersensitivity to DNA damaging agents and replication stress, shortened lifespan, genome instability and mitotic hyper-recombination, making them invaluable model systems for elucidating eukaryotic RecQ helicase function. Yeast and human RecQ helicases have common DNA substrates and domain structures and share similar physical interaction partners. Here, we review the major cellular functions of the yeast RecQ helicases Sgs1 of Saccharomyces cerevisiae and Rqh1 of Schizosaccharomyces pombe and provide an outlook on some of the outstanding questions in the field.
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Affiliation(s)
- Sonia Vidushi Gupta
- Department of Cell Biology, Microbiology and Molecular Biology, University of South, Florida, Tampa, FL 33620, USA;
| | - Kristina Hildegard 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
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Li Y, Shen J, Niu H. DNA duplex recognition activates Exo1 nuclease activity. J Biol Chem 2019; 294:11559-11567. [PMID: 31182486 DOI: 10.1074/jbc.ra119.008549] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/09/2019] [Indexed: 11/06/2022] Open
Abstract
Exonuclease 1 (Exo1) is an evolutionarily conserved eukaryotic nuclease that plays a multifaceted role in maintaining genome stability. The biochemical attributes of Exo1 have been extensively characterized via conventional assays. However, the key step governing its activation remains elusive. Extending the previous finding that Exo1 can digest a randomly selected single-stranded DNA (ssDNA) but not a poly(dT) oligonucleotide and using purified recombinant Exo1 and nuclease and electrophoretic mobility shift assays, here we determined that DNA hairpins with a stem size of 4 bp or longer are able to activate Exo1-mediated digestion of ssDNA. We further provide evidence suggesting that Exo1 uses an evolutionarily conserved residue, Lys185 This residue interacted with the phosphate group bridging the third and fourth nucleotide on the digestion strand of the substrate DNA for duplex recognition, critical for Exo1 activation on not only ssDNA but also dsDNA. Additionally, the defect of an exo1-K185A mutant in duplex digestion was partially rescued by longer overhanging DNA. However, we noted that the enhanced Exo1 nuclease activity by longer overhanging DNA is largely eliminated by replication protein A (RPA), likely because of the previously reported RPA activity that strips Exo1 off the ssDNA. We conclude that duplex DNA contact by Exo1 is a general mechanism that controls its activation and that this mechanism is particularly important for digestion of duplex DNA whose nascent ssDNA is bound by RPA.
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Affiliation(s)
- Yuxi Li
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405.,Interdisciplinary Biochemistry Program, Indiana University, Bloomington, Indiana 47405
| | - Jiangchuan Shen
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405
| | - Hengyao Niu
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405
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Liu Y, Guo Z, Zhao C, Li X, Liu H, Chen J. Lymphangioleiomyomatosis: a case report and review of diagnosis and treatment. Onco Targets Ther 2018; 11:5339-5347. [PMID: 30214240 PMCID: PMC6126514 DOI: 10.2147/ott.s161360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Lymphangioleiomyomatosis (LAM) is a rare disease that generally affects young women and involves the abnormal proliferation of smooth muscle-like cells (LAM cells) in the lungs (pulmonary LAM) and extrapulmonary sites (extrapulmonary LAM). This disease is rare in males. It is hard to distinguish between lung cancer and pulmonary LAM, especially during early stages. Herein, we present a case of a 66-year-old man with a small nodule in the right upper lobe that was first diagnosed as a lung malignancy using a chest CT scan. After a wedge dissection, a pathologist performed a histologic and immunohistochemical examination, and a diagnosis of pulmonary LAM was made. We further performed a 518-gene panel analysis using next-generation sequencing, and only three genes, BARD1, BLM, and BRCA2, were found to have mutations. We also provide a summary of the diagnosis and treatment of this disease.
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Affiliation(s)
- Yi Liu
- Department of Lung Cancer Surgery, Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin 300052, China,
| | - Zhibin Guo
- Department of Lung Cancer Surgery, Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin 300052, China,
| | - Chenlong Zhao
- Department of Lung Cancer Surgery, Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin 300052, China,
| | - Xin Li
- Department of Lung Cancer Surgery, Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin 300052, China,
| | - Hongyu Liu
- Department of Lung Cancer Surgery, Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin 300052, China,
| | - Jun Chen
- Department of Lung Cancer Surgery, Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin 300052, China,
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Sgs1 Binding to Rad51 Stimulates Homology-Directed DNA Repair in Saccharomyces cerevisiae. Genetics 2017; 208:125-138. [PMID: 29162625 PMCID: PMC5753853 DOI: 10.1534/genetics.117.300545] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 11/16/2017] [Indexed: 12/23/2022] Open
Abstract
Accurate repair of DNA breaks is essential to maintain genome integrity and cellular fitness. Sgs1, the sole member of the RecQ family of DNA helicases in Saccharomyces cerevisiae, is important for both early and late stages of homology-dependent repair. Its large number of physical and genetic interactions with DNA recombination, repair, and replication factors has established Sgs1 as a key player in the maintenance of genome integrity. To determine the significance of Sgs1 binding to the strand-exchange factor Rad51, we have identified a single amino acid change at the C-terminal of the helicase core of Sgs1 that disrupts Rad51 binding. In contrast to an SGS1 deletion or a helicase-defective sgs1 allele, this new separation-of-function allele, sgs1-FD, does not cause DNA damage hypersensitivity or genome instability, but exhibits negative and positive genetic interactions with sae2Δ, mre11Δ, exo1Δ, srs2Δ, rrm3Δ, and pol32Δ that are distinct from those of known sgs1 mutants. Our findings suggest that the Sgs1-Rad51 interaction stimulates homologous recombination (HR). However, unlike sgs1 mutations, which impair the resection of DNA double-strand ends, negative genetic interactions of the sgs1-FD allele are not suppressed by YKU70 deletion. We propose that the Sgs1-Rad51 interaction stimulates HR by facilitating the formation of the presynaptic Rad51 filament, possibly by Sgs1 competing with single-stranded DNA for replication protein A binding during resection.
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Pathways and Mechanisms that Prevent Genome Instability in Saccharomyces cerevisiae. Genetics 2017; 206:1187-1225. [PMID: 28684602 PMCID: PMC5500125 DOI: 10.1534/genetics.112.145805] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 04/26/2017] [Indexed: 12/13/2022] Open
Abstract
Genome rearrangements result in mutations that underlie many human diseases, and ongoing genome instability likely contributes to the development of many cancers. The tools for studying genome instability in mammalian cells are limited, whereas model organisms such as Saccharomyces cerevisiae are more amenable to these studies. Here, we discuss the many genetic assays developed to measure the rate of occurrence of Gross Chromosomal Rearrangements (called GCRs) in S. cerevisiae. These genetic assays have been used to identify many types of GCRs, including translocations, interstitial deletions, and broken chromosomes healed by de novo telomere addition, and have identified genes that act in the suppression and formation of GCRs. Insights from these studies have contributed to the understanding of pathways and mechanisms that suppress genome instability and how these pathways cooperate with each other. Integrated models for the formation and suppression of GCRs are discussed.
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Stalled replication forks generate a distinct mutational signature in yeast. Proc Natl Acad Sci U S A 2017; 114:9665-9670. [PMID: 28827358 DOI: 10.1073/pnas.1706640114] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proliferating cells acquire genome alterations during the act of DNA replication. This leads to mutation accumulation and somatic cell mosaicism in multicellular organisms, and is also implicated as an underlying cause of aging and tumorigenesis. The molecular mechanisms of DNA replication-associated genome rearrangements are poorly understood, largely due to methodological difficulties in analyzing specific replication forks in vivo. To provide an insight into this process, we analyzed the mutagenic consequences of replication fork stalling at a single, site-specific replication barrier (the Escherichia coli Tus/Ter complex) engineered into the yeast genome. We demonstrate that transient stalling at this barrier induces a distinct pattern of genome rearrangements in the newly replicated region behind the stalled fork, which primarily consist of localized losses and duplications of DNA sequences. These genetic alterations arise through the aberrant repair of a single-stranded DNA gap, in a process that is dependent on Exo1- and Shu1-dependent homologous recombination repair (HRR). Furthermore, aberrant processing of HRR intermediates, and elevated HRR-associated mutagenesis, is detectable in a yeast model of the human cancer predisposition disorder, Bloom's syndrome. Our data reveal a mechanism by which cellular responses to stalled replication forks can actively generate genomic alterations and genetic diversity in normal proliferating cells.
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Hypermutation signature reveals a slippage and realignment model of translesion synthesis by Rev3 polymerase in cisplatin-treated yeast. Proc Natl Acad Sci U S A 2017; 114:2663-2668. [PMID: 28223526 DOI: 10.1073/pnas.1618555114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Gene-gene or gene-drug interactions are typically quantified using fitness as a readout because the data are continuous and easily measured in high throughput. However, to what extent fitness captures the range of other phenotypes that show synergistic effects is usually unknown. Using Saccharomyces cerevisiae and focusing on a matrix of DNA repair mutants and genotoxic drugs, we quantify 76 gene-drug interactions based on both mutation rate and fitness and find that these parameters are not connected. Independent of fitness defects, we identified six cases of synthetic hypermutation, where the combined effect of the drug and mutant on mutation rate was greater than predicted. One example occurred when yeast lacking RAD1 were exposed to cisplatin, and we characterized this interaction using whole-genome sequencing. Our sequencing results indicate mutagenesis by cisplatin in rad1Δ cells appeared to depend almost entirely on interstrand cross-links at GpCpN motifs. Interestingly, our data suggest that the following base on the template strand dictates the addition of the mutated base. This result differs from cisplatin mutation signatures in XPF-deficient Caenorhabditis elegans and supports a model in which translesion synthesis polymerases perform a slippage and realignment extension across from the damaged base. Accordingly, DNA polymerase ζ activity was essential for mutagenesis in cisplatin-treated rad1Δ cells. Together these data reveal the potential to gain new mechanistic insights from nonfitness measures of gene-drug interactions and extend the use of mutation accumulation and whole-genome sequencing analysis to define DNA repair mechanisms.
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Silva S, Altmannova V, Eckert-Boulet N, Kolesar P, Gallina I, Hang L, Chung I, Arneric M, Zhao X, Buron LD, Mortensen UH, Krejci L, Lisby M. SUMOylation of Rad52-Rad59 synergistically change the outcome of mitotic recombination. DNA Repair (Amst) 2016; 42:11-25. [PMID: 27130983 DOI: 10.1016/j.dnarep.2016.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/02/2016] [Accepted: 04/05/2016] [Indexed: 11/18/2022]
Abstract
Homologous recombination (HR) is essential for maintenance of genome stability through double-strand break (DSB) repair, but at the same time HR can lead to loss of heterozygosity and uncontrolled recombination can be genotoxic. The post-translational modification by SUMO (small ubiquitin-like modifier) has been shown to modulate recombination, but the exact mechanism of this regulation remains unclear. Here we show that SUMOylation stabilizes the interaction between the recombination mediator Rad52 and its paralogue Rad59 in Saccharomyces cerevisiae. Although Rad59 SUMOylation is not required for survival after genotoxic stress, it affects the outcome of recombination to promote conservative DNA repair. In some genetic assays, Rad52 and Rad59 SUMOylation act synergistically. Collectively, our data indicate that the described SUMO modifications affect the balance between conservative and non-conservative mechanisms of HR.
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Affiliation(s)
- Sonia Silva
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Veronika Altmannova
- Department of Biology, Masaryk University, Kamenice 5/A7, 62500 Brno, Czech Republic
| | - Nadine Eckert-Boulet
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Peter Kolesar
- Department of Biology, Masaryk University, Kamenice 5/A7, 62500 Brno, Czech Republic
| | - Irene Gallina
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Lisa Hang
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Inn Chung
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Milica Arneric
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Xiaolan Zhao
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Line Due Buron
- Department of Systems Biology, Technical University of Denmark, Building 223, 2800 Kgs. Lyngby, Denmark
| | - Uffe H Mortensen
- Department of Systems Biology, Technical University of Denmark, Building 223, 2800 Kgs. Lyngby, Denmark
| | - Lumir Krejci
- Department of Biology, Masaryk University, Kamenice 5/A7, 62500 Brno, Czech Republic; National Centre for Biomolecular Research, Masaryk University, Kamenice 5/A4, Brno 625 00, Czech Republic; International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital Brno, Brno, Czech Republic
| | - Michael Lisby
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
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Doerfler L, Schmidt KH. Exo1 phosphorylation status controls the hydroxyurea sensitivity of cells lacking the Pol32 subunit of DNA polymerases delta and zeta. DNA Repair (Amst) 2015; 24:26-36. [PMID: 25457771 DOI: 10.1016/j.dnarep.2014.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 09/29/2014] [Accepted: 10/02/2014] [Indexed: 11/16/2022]
Abstract
Exo1 belongs to the Rad2 family of structure-specific nucleases and possesses 5'-3' exonuclease activity on double-stranded DNA substrates. Exo1 interacts physically with the DNA mismatch repair (MMR) proteins Msh2 and Mlh1 and is involved in the excision of the mispaired nucleotide. Independent of its role in MMR, Exo1 contributes to long-range resection of DNA double-strand break (DSB) ends to facilitate their repair by homologous recombination (HR), and was recently identified as a component of error-free DNA damage tolerance pathways. Here, we show that Exo1 activity increases the hydroxyurea sensitivity of cells lacking Pol32, a subunit of DNA polymerases δ and ζ. Both, phospho-mimicking and dephospho-mimicking exo1 mutants act as hypermorphs, as evidenced by an increase in HU sensitivity of pol32Δ cells, suggesting that they are trapped in an active form and that phosphorylation of Exo1 at residues S372, S567, S587, S692 is necessary, but insufficient, for the accurate regulation of Exo1 activity at stalled replication forks. In contrast, neither phosphorylation status is important for Exo1's role in MMR or in the suppression of genome instability in cells lacking Sgs1 helicase. This ability of an EXO1 deletion to suppress the HU hypersensitivity of pol32Δ cells is in contrast to the negative genetic interaction between deletions of EXO1 and POL32 in MMS-treated cells as well as the role of EXO1 in DNA-damage treated rad53 and mec1 mutants.
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Affiliation(s)
- Lillian Doerfler
- Department of Cell Biology, Microbiology and Molecular Biology, 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 Cell Biology, Microbiology 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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