1
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Roshan P, Kuppa S, Mattice JR, Kaushik V, Chadda R, Pokhrel N, Tumala BR, Biswas A, Bothner B, Antony E, Origanti S. An Aurora B-RPA signaling axis secures chromosome segregation fidelity. Nat Commun 2023; 14:3008. [PMID: 37230964 PMCID: PMC10212944 DOI: 10.1038/s41467-023-38711-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 05/09/2023] [Indexed: 05/27/2023] Open
Abstract
Errors in chromosome segregation underlie genomic instability associated with cancers. Resolution of replication and recombination intermediates and protection of vulnerable single-stranded DNA (ssDNA) intermediates during mitotic progression requires the ssDNA binding protein Replication Protein A (RPA). However, the mechanisms that regulate RPA specifically during unperturbed mitotic progression are poorly resolved. RPA is a heterotrimer composed of RPA70, RPA32 and RPA14 subunits and is predominantly regulated through hyperphosphorylation of RPA32 in response to DNA damage. Here, we have uncovered a mitosis-specific regulation of RPA by Aurora B kinase. Aurora B phosphorylates Ser-384 in the DNA binding domain B of the large RPA70 subunit and highlights a mode of regulation distinct from RPA32. Disruption of Ser-384 phosphorylation in RPA70 leads to defects in chromosome segregation with loss of viability and a feedback modulation of Aurora B activity. Phosphorylation at Ser-384 remodels the protein interaction domains of RPA. Furthermore, phosphorylation impairs RPA binding to DSS1 that likely suppresses homologous recombination during mitosis by preventing recruitment of DSS1-BRCA2 to exposed ssDNA. We showcase a critical Aurora B-RPA signaling axis in mitosis that is essential for maintaining genomic integrity.
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Affiliation(s)
- Poonam Roshan
- Department of Biology, St. Louis University, St. Louis, MO, 63103, USA
| | - Sahiti Kuppa
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO, 63104, USA
| | - Jenna R Mattice
- Department of Biochemistry, Montana State University, Bozeman, MT, 59717, USA
| | - Vikas Kaushik
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO, 63104, USA
| | - Rahul Chadda
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO, 63104, USA
| | - Nilisha Pokhrel
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53217, USA
| | - Brunda R Tumala
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO, 63104, USA
| | - Aparna Biswas
- Department of Biology, St. Louis University, St. Louis, MO, 63103, USA
| | - Brian Bothner
- Department of Biochemistry, Montana State University, Bozeman, MT, 59717, USA
| | - Edwin Antony
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO, 63104, USA.
| | - Sofia Origanti
- Department of Biology, St. Louis University, St. Louis, MO, 63103, USA.
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2
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Xu YJ, Bhadra S, Mahdi ATA, Dev K, Yurtsever I, Nakamura TM. Comprehensive mutational analysis of the checkpoint signaling function of Rpa1/Ssb1 in fission yeast. PLoS Genet 2023; 19:e1010691. [PMID: 37200372 DOI: 10.1371/journal.pgen.1010691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 05/31/2023] [Accepted: 04/24/2023] [Indexed: 05/20/2023] Open
Abstract
Replication protein A (RPA) is a heterotrimeric complex and the major single-strand DNA (ssDNA) binding protein in eukaryotes. It plays important roles in DNA replication, repair, recombination, telomere maintenance, and checkpoint signaling. Because RPA is essential for cell survival, understanding its checkpoint signaling function in cells has been challenging. Several RPA mutants have been reported previously in fission yeast. None of them, however, has a defined checkpoint defect. A separation-of-function mutant of RPA, if identified, would provide significant insights into the checkpoint initiation mechanisms. We have explored this possibility and carried out an extensive genetic screen for Rpa1/Ssb1, the large subunit of RPA in fission yeast, looking for mutants with defects in checkpoint signaling. This screen has identified twenty-five primary mutants that are sensitive to genotoxins. Among these mutants, two have been confirmed partially defective in checkpoint signaling primarily at the replication fork, not the DNA damage site. The remaining mutants are likely defective in other functions such as DNA repair or telomere maintenance. Our screened mutants, therefore, provide a valuable tool for future dissection of the multiple functions of RPA in fission yeast.
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Affiliation(s)
- Yong-Jie Xu
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, United States of America
| | - Sankhadip Bhadra
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, United States of America
| | - Alaa Taha A Mahdi
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, United States of America
| | - Kamal Dev
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, United States of America
| | - Ilknur Yurtsever
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, United States of America
| | - Toru M Nakamura
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, Illinois, United States of America
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3
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Scherzer M, Giordano F, Ferran MS, Ström L. Recruitment of Scc2/4 to double-strand breaks depends on γH2A and DNA end resection. Life Sci Alliance 2022; 5:e202101244. [PMID: 35086935 PMCID: PMC8807874 DOI: 10.26508/lsa.202101244] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 01/13/2022] [Accepted: 01/14/2022] [Indexed: 12/15/2022] Open
Abstract
Homologous recombination enables cells to overcome the threat of DNA double-strand breaks (DSBs), allowing for repair without the loss of genetic information. Central to the homologous recombination repair process is the de novo loading of cohesin around a DSB by its loader complex Scc2/4. Although cohesin's DSB accumulation has been explored in numerous studies, the prerequisites for Scc2/4 recruitment during the repair process are still elusive. To address this question, we combine chromatin immunoprecipitation-qPCR with a site-specific DSB in vivo, in Saccharomyces cerevisiae We find that Scc2 DSB recruitment relies on γH2A and Tel1, but as opposed to cohesin, not on Mec1. We further show that the binding of Scc2, which emanates from the break site, depends on and coincides with DNA end resection. Absence of chromatin remodeling at the DSB affects Scc2 binding and DNA end resection to a comparable degree, further indicating the latter to be a major driver for Scc2 recruitment. Our results shed light on the intricate DSB repair cascade leading to the recruitment of Scc2/4 and subsequent loading of cohesin.
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Affiliation(s)
- Martin Scherzer
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Fosco Giordano
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Maria Solé Ferran
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Lena Ström
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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4
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The Role of the Rad55-Rad57 Complex in DNA Repair. Genes (Basel) 2021; 12:genes12091390. [PMID: 34573372 PMCID: PMC8472222 DOI: 10.3390/genes12091390] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 08/30/2021] [Accepted: 09/03/2021] [Indexed: 11/29/2022] Open
Abstract
Homologous recombination (HR) is a mechanism conserved from bacteria to humans essential for the accurate repair of DNA double-stranded breaks, and maintenance of genome integrity. In eukaryotes, the key DNA transactions in HR are catalyzed by the Rad51 recombinase, assisted by a host of regulatory factors including mediators such as Rad52 and Rad51 paralogs. Rad51 paralogs play a crucial role in regulating proper levels of HR, and mutations in the human counterparts have been associated with diseases such as cancer and Fanconi Anemia. In this review, we focus on the Saccharomyces cerevisiae Rad51 paralog complex Rad55–Rad57, which has served as a model for understanding the conserved role of Rad51 paralogs in higher eukaryotes. Here, we discuss the results from early genetic studies, biochemical assays, and new single-molecule observations that have together contributed to our current understanding of the molecular role of Rad55–Rad57 in HR.
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5
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Ju MK, Shin KJ, Lee JR, Khim KW, A Lee E, Ra JS, Kim BG, Jo HS, Yoon JH, Kim TM, Myung K, Choi JH, Kim H, Chae YC. NSMF promotes the replication stress-induced DNA damage response for genome maintenance. Nucleic Acids Res 2021; 49:5605-5622. [PMID: 33963872 PMCID: PMC8191778 DOI: 10.1093/nar/gkab311] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 04/14/2021] [Accepted: 04/16/2021] [Indexed: 11/14/2022] Open
Abstract
Proper activation of DNA repair pathways in response to DNA replication stress is critical for maintaining genomic integrity. Due to the complex nature of the replication fork (RF), problems at the RF require multiple proteins, some of which remain unidentified, for resolution. In this study, we identified the N-methyl-D-aspartate receptor synaptonuclear signaling and neuronal migration factor (NSMF) as a key replication stress response factor that is important for ataxia telangiectasia and Rad3-related protein (ATR) activation. NSMF localizes rapidly to stalled RFs and acts as a scaffold to modulate replication protein A (RPA) complex formation with cell division cycle 5-like (CDC5L) and ATR/ATR-interacting protein (ATRIP). Depletion of NSMF compromised phosphorylation and ubiquitination of RPA2 and the ATR signaling cascade, resulting in genomic instability at RFs under DNA replication stress. Consistently, NSMF knockout mice exhibited increased genomic instability and hypersensitivity to genotoxic stress. NSMF deficiency in human and mouse cells also caused increased chromosomal instability. Collectively, these findings demonstrate that NSMF regulates the ATR pathway and the replication stress response network for genome maintenance and cell survival.
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Affiliation(s)
- Min Kyung Ju
- Department of Life Sciences, Ulsan National University of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Kyeong Jin Shin
- Department of Life Sciences, Ulsan National University of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Joo Rak Lee
- Department of Life Sciences, Ulsan National University of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Keon Woo Khim
- Department of Life Sciences, Ulsan National University of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Eun A Lee
- Center for Genomic Integrity Institute for Basic Science (IBS), UNIST, Ulsan 44919, Republic of Korea
| | - Jae Sun Ra
- Center for Genomic Integrity Institute for Basic Science (IBS), UNIST, Ulsan 44919, Republic of Korea
| | - Byung-Gyu Kim
- Center for Genomic Integrity Institute for Basic Science (IBS), UNIST, Ulsan 44919, Republic of Korea
| | - Han-Seul Jo
- Neurodegenerative Diseases Research Group, Korea Brain Research Institute, Daegu 41062, Republic of Korea
| | - Jong Hyuk Yoon
- Neurodegenerative Diseases Research Group, Korea Brain Research Institute, Daegu 41062, Republic of Korea
| | - Tae Moon Kim
- Center for Genomic Integrity Institute for Basic Science (IBS), UNIST, Ulsan 44919, Republic of Korea
| | - Kyungjae Myung
- Center for Genomic Integrity Institute for Basic Science (IBS), UNIST, Ulsan 44919, Republic of Korea.,Department of Biomedical Engineering, Ulsan National University of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Jang Hyun Choi
- Department of Life Sciences, Ulsan National University of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Hongtae Kim
- Department of Life Sciences, Ulsan National University of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.,Center for Genomic Integrity Institute for Basic Science (IBS), UNIST, Ulsan 44919, Republic of Korea
| | - Young Chan Chae
- Department of Life Sciences, Ulsan National University of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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6
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Caldwell CC, Spies M. Dynamic elements of replication protein A at the crossroads of DNA replication, recombination, and repair. Crit Rev Biochem Mol Biol 2020; 55:482-507. [PMID: 32856505 PMCID: PMC7821911 DOI: 10.1080/10409238.2020.1813070] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/18/2020] [Accepted: 08/18/2020] [Indexed: 01/19/2023]
Abstract
The heterotrimeric eukaryotic Replication protein A (RPA) is a master regulator of numerous DNA metabolic processes. For a long time, it has been viewed as an inert protector of ssDNA and a platform for assembly of various genome maintenance and signaling machines. Later, the modular organization of the RPA DNA binding domains suggested a possibility for dynamic interaction with ssDNA. This modular organization has inspired several models for the RPA-ssDNA interaction that aimed to explain how RPA, the high-affinity ssDNA binding protein, is replaced by the downstream players in DNA replication, recombination, and repair that bind ssDNA with much lower affinity. Recent studies, and in particular single-molecule observations of RPA-ssDNA interactions, led to the development of a new model for the ssDNA handoff from RPA to a specific downstream factor where not only stability and structural rearrangements but also RPA conformational dynamics guide the ssDNA handoff. Here we will review the current knowledge of the RPA structure, its dynamic interaction with ssDNA, and how RPA conformational dynamics may be influenced by posttranslational modification and proteins that interact with RPA, as well as how RPA dynamics may be harnessed in cellular decision making.
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Affiliation(s)
- Colleen C. Caldwell
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - Maria Spies
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
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7
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Dueva R, Iliakis G. Replication protein A: a multifunctional protein with roles in DNA replication, repair and beyond. NAR Cancer 2020; 2:zcaa022. [PMID: 34316690 PMCID: PMC8210275 DOI: 10.1093/narcan/zcaa022] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/23/2020] [Accepted: 08/27/2020] [Indexed: 02/07/2023] Open
Abstract
Single-stranded DNA (ssDNA) forms continuously during DNA replication and is an important intermediate during recombination-mediated repair of damaged DNA. Replication protein A (RPA) is the major eukaryotic ssDNA-binding protein. As such, RPA protects the transiently formed ssDNA from nucleolytic degradation and serves as a physical platform for the recruitment of DNA damage response factors. Prominent and well-studied RPA-interacting partners are the tumor suppressor protein p53, the RAD51 recombinase and the ATR-interacting proteins ATRIP and ETAA1. RPA interactions are also documented with the helicases BLM, WRN and SMARCAL1/HARP, as well as the nucleotide excision repair proteins XPA, XPG and XPF–ERCC1. Besides its well-studied roles in DNA replication (restart) and repair, accumulating evidence shows that RPA is engaged in DNA activities in a broader biological context, including nucleosome assembly on nascent chromatin, regulation of gene expression, telomere maintenance and numerous other aspects of nucleic acid metabolism. In addition, novel RPA inhibitors show promising effects in cancer treatment, as single agents or in combination with chemotherapeutics. Since the biochemical properties of RPA and its roles in DNA repair have been extensively reviewed, here we focus on recent discoveries describing several non-canonical functions.
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Affiliation(s)
- Rositsa Dueva
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
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8
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Yates LA, Aramayo RJ, Pokhrel N, Caldwell CC, Kaplan JA, Perera RL, Spies M, Antony E, Zhang X. A structural and dynamic model for the assembly of Replication Protein A on single-stranded DNA. Nat Commun 2018; 9:5447. [PMID: 30575763 PMCID: PMC6303327 DOI: 10.1038/s41467-018-07883-7] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 12/03/2018] [Indexed: 12/04/2022] Open
Abstract
Replication Protein A (RPA), the major eukaryotic single stranded DNA-binding protein, binds to exposed ssDNA to protect it from nucleases, participates in a myriad of nucleic acid transactions and coordinates the recruitment of other important players. RPA is a heterotrimer and coats long stretches of single-stranded DNA (ssDNA). The precise molecular architecture of the RPA subunits and its DNA binding domains (DBDs) during assembly is poorly understood. Using cryo electron microscopy we obtained a 3D reconstruction of the RPA trimerisation core bound with ssDNA (∼55 kDa) at ∼4.7 Å resolution and a dimeric RPA assembly on ssDNA. FRET-based solution studies reveal dynamic rearrangements of DBDs during coordinated RPA binding and this activity is regulated by phosphorylation at S178 in RPA70. We present a structural model on how dynamic DBDs promote the cooperative assembly of multiple RPAs on long ssDNA.
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Affiliation(s)
- Luke A Yates
- Section of Structural Biology, Department of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London, SW7 2AZ, UK
| | - Ricardo J Aramayo
- Section of Structural Biology, Department of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London, SW7 2AZ, UK
| | - Nilisha Pokhrel
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53201, USA
| | - Colleen C Caldwell
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52241, USA
| | - Joshua A Kaplan
- Section of Structural Biology, Department of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London, SW7 2AZ, UK
| | - Rajika L Perera
- Section of Structural Biology, Department of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London, SW7 2AZ, UK
- Poseidon LLC, 2265 East Foothill Boulevard, Pasadena, CA, 91107, USA
| | - Maria Spies
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52241, USA
| | - Edwin Antony
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53201, USA
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London, SW7 2AZ, UK.
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9
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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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10
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Shkedy D, Singh N, Shemesh K, Amir A, Geiger T, Liefshitz B, Harari Y, Kupiec M. Regulation of Elg1 activity by phosphorylation. Cell Cycle 2016; 14:3689-97. [PMID: 26177013 DOI: 10.1080/15384101.2015.1068475] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
ELG1 is a conserved gene with important roles in the maintenance of genome stability. Elg1's activity prevents gross chromosomal rearrangements, maintains proper telomere length regulation, helps repairing DNA damage created by a number of genotoxins and participates in sister chromatid cohesion. Elg1 is evolutionarily conserved, and its Fanconi Anemia-related mammalian ortholog (also known as ATAD5) is embryonic lethal when lost in mice and acts as a tumor suppressor in mice and humans. Elg1 encodes a protein that forms an RFC-like complex that unloads the replicative clamp, PCNA, from DNA, mainly in its SUMOylated form. We have identified 2 different regions in yeast Elg1 that undergo phosphorylation. Phosphorylation of one of them, S112, is dependent on the ATR yeast ortholog, Mec1, and probably is a direct target of this kinase. We show that phosphorylation of Elg1 is important for its role at telomeres. Mutants unable to undergo phosphorylation suppress the DNA damage sensitivity of Δrad5 mutants, defective for an error-free post-replicational bypass pathway. This indicates a role of phosphorylation in the regulation of DNA repair. Our results open the way to investigate the mechanisms by which the activity of Elg1 is regulated during DNA replication and in response to DNA damage.
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Affiliation(s)
- Dganit Shkedy
- a Department of Molecular Microbiology and Biotechnology ; Tel Aviv University ; Ramat Aviv , Israel
| | - Nishant Singh
- a Department of Molecular Microbiology and Biotechnology ; Tel Aviv University ; Ramat Aviv , Israel
| | - Keren Shemesh
- a Department of Molecular Microbiology and Biotechnology ; Tel Aviv University ; Ramat Aviv , Israel
| | - Ayelet Amir
- a Department of Molecular Microbiology and Biotechnology ; Tel Aviv University ; Ramat Aviv , Israel
| | - Tamar Geiger
- b Department of Human Molecular Genetics and Biochemistry ; Sackler Faculty of Medicine; Tel Aviv University ; Ramat Aviv , Israel
| | - Batia Liefshitz
- a Department of Molecular Microbiology and Biotechnology ; Tel Aviv University ; Ramat Aviv , Israel
| | - Yaniv Harari
- a Department of Molecular Microbiology and Biotechnology ; Tel Aviv University ; Ramat Aviv , Israel
| | - Martin Kupiec
- a Department of Molecular Microbiology and Biotechnology ; Tel Aviv University ; Ramat Aviv , Israel
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11
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Sawicka M, Wanrooij PH, Darbari VC, Tannous E, Hailemariam S, Bose D, Makarova AV, Burgers PM, Zhang X. The Dimeric Architecture of Checkpoint Kinases Mec1ATR and Tel1ATM Reveal a Common Structural Organization. J Biol Chem 2016; 291:13436-47. [PMID: 27129217 PMCID: PMC4919432 DOI: 10.1074/jbc.m115.708263] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Indexed: 12/21/2022] Open
Abstract
The phosphatidylinositol 3-kinase-related protein kinases are key regulators controlling a wide range of cellular events. The yeast Tel1 and Mec1·Ddc2 complex (ATM and ATR-ATRIP in humans) play pivotal roles in DNA replication, DNA damage signaling, and repair. Here, we present the first structural insight for dimers of Mec1·Ddc2 and Tel1 using single-particle electron microscopy. Both kinases reveal a head to head dimer with one major dimeric interface through the N-terminal HEAT (named after Huntingtin, elongation factor 3, protein phosphatase 2A, and yeast kinase TOR1) repeat. Their dimeric interface is significantly distinct from the interface of mTOR complex 1 dimer, which oligomerizes through two spatially separate interfaces. We also observe different structural organizations of kinase domains of Mec1 and Tel1. The kinase domains in the Mec1·Ddc2 dimer are located in close proximity to each other. However, in the Tel1 dimer they are fully separated, providing potential access of substrates to this kinase, even in its dimeric form.
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Affiliation(s)
- Marta Sawicka
- From the Section of Structural Biology, Department of Medicine, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom and
| | - Paulina H Wanrooij
- the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Vidya C Darbari
- From the Section of Structural Biology, Department of Medicine, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom and
| | - Elias Tannous
- the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Sarem Hailemariam
- the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Daniel Bose
- From the Section of Structural Biology, Department of Medicine, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom and
| | - Alena V Makarova
- the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Peter M Burgers
- the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Xiaodong Zhang
- From the Section of Structural Biology, Department of Medicine, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom and
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12
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Abstract
The repair of DNA double-strand breaks (DSBs) by homologous recombination (HR) is initiated by nucleolytic degradation of the 5'-terminated strands in a process termed end resection. End resection generates 3'-single-stranded DNA tails, substrates for Rad51 to catalyze homologous pairing and DNA strand exchange, and for activation of the DNA damage checkpoint. The commonly accepted view is that end resection occurs by a two-step mechanism. In the first step, Sae2/CtIP activates the Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex to endonucleolytically cleave the 5'-terminated DNA strands close to break ends, and in the second step Exo1 and/or Dna2 nucleases extend the resected tracts to produce long 3'-ssDNA-tailed intermediates. Initiation of resection commits a cell to repair a DSB by HR because long ssDNA overhangs are poor substrates for non-homologous end joining (NHEJ). Thus, the initiation of end resection has emerged as a critical control point for repair pathway choice. Here, I review recent studies on the mechanism of end resection and how this process is regulated to ensure the most appropriate repair outcome.
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Affiliation(s)
- Lorraine S Symington
- a Department of Microbiology & Immunology , Columbia University Medical Center , New York , USA
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13
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Managing Single-Stranded DNA during Replication Stress in Fission Yeast. Biomolecules 2015; 5:2123-39. [PMID: 26393661 PMCID: PMC4598791 DOI: 10.3390/biom5032123] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 08/28/2015] [Accepted: 09/01/2015] [Indexed: 01/27/2023] Open
Abstract
Replication fork stalling generates a variety of responses, most of which cause an increase in single-stranded DNA. ssDNA is a primary signal of replication distress that activates cellular checkpoints. It is also a potential source of genome instability and a substrate for mutation and recombination. Therefore, managing ssDNA levels is crucial to chromosome integrity. Limited ssDNA accumulation occurs in wild-type cells under stress. In contrast, cells lacking the replication checkpoint cannot arrest forks properly and accumulate large amounts of ssDNA. This likely occurs when the replication fork polymerase and helicase units are uncoupled. Some cells with mutations in the replication helicase (mcm-ts) mimic checkpoint-deficient cells, and accumulate extensive areas of ssDNA to trigger the G2-checkpoint. Another category of helicase mutant (mcm4-degron) causes fork stalling in early S-phase due to immediate loss of helicase function. Intriguingly, cells realize that ssDNA is present, but fail to detect that they accumulate ssDNA, and continue to divide. Thus, the cellular response to replication stalling depends on checkpoint activity and the time that replication stress occurs in S-phase. In this review we describe the signs, signals, and symptoms of replication arrest from an ssDNA perspective. We explore the possible mechanisms for these effects. We also advise the need for caution when detecting and interpreting data related to the accumulation of ssDNA.
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14
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Balint A, Kim T, Gallo D, Cussiol JR, Bastos de Oliveira FM, Yimit A, Ou J, Nakato R, Gurevich A, Shirahige K, Smolka MB, Zhang Z, Brown GW. Assembly of Slx4 signaling complexes behind DNA replication forks. EMBO J 2015; 34:2182-97. [PMID: 26113155 DOI: 10.15252/embj.201591190] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 06/02/2015] [Indexed: 12/30/2022] Open
Abstract
Obstructions to replication fork progression, referred to collectively as DNA replication stress, challenge genome stability. In Saccharomyces cerevisiae, cells lacking RTT107 or SLX4 show genome instability and sensitivity to DNA replication stress and are defective in the completion of DNA replication during recovery from replication stress. We demonstrate that Slx4 is recruited to chromatin behind stressed replication forks, in a region that is spatially distinct from that occupied by the replication machinery. Slx4 complex formation is nucleated by Mec1 phosphorylation of histone H2A, which is recognized by the constitutive Slx4 binding partner Rtt107. Slx4 is essential for recruiting the Mec1 activator Dpb11 behind stressed replication forks, and Slx4 complexes are important for full activity of Mec1. We propose that Slx4 complexes promote robust checkpoint signaling by Mec1 by stably recruiting Dpb11 within a discrete domain behind the replication fork, during DNA replication stress.
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Affiliation(s)
- Attila Balint
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - TaeHyung Kim
- Donnelly Centre, University of Toronto, Toronto, ON, Canada Department of Computer Science, University of Toronto, Toronto, ON, Canada
| | - David Gallo
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Jose Renato Cussiol
- Department of Molecular Biology and Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Francisco M Bastos de Oliveira
- Department of Molecular Biology and Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Askar Yimit
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Jiongwen Ou
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Ryuichiro Nakato
- Institute of Molecular and Cellular Biosciences, Research Center for Epigenetic Disease, University of Tokyo, Tokyo, Japan
| | - Alexey Gurevich
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Katsuhiko Shirahige
- Institute of Molecular and Cellular Biosciences, Research Center for Epigenetic Disease, University of Tokyo, Tokyo, Japan
| | - Marcus B Smolka
- Department of Molecular Biology and Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Zhaolei Zhang
- Donnelly Centre, University of Toronto, Toronto, ON, Canada Department of Computer Science, University of Toronto, Toronto, ON, Canada
| | - Grant W Brown
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
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15
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Tsabar M, Mason JM, Chan YL, Bishop DK, Haber JE. Caffeine inhibits gene conversion by displacing Rad51 from ssDNA. Nucleic Acids Res 2015; 43:6902-18. [PMID: 26019181 PMCID: PMC4538809 DOI: 10.1093/nar/gkv525] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 05/07/2015] [Indexed: 01/08/2023] Open
Abstract
Efficient repair of chromosomal double-strand breaks (DSBs) by homologous recombination relies on the formation of a Rad51 recombinase filament that forms on single-stranded DNA (ssDNA) created at DSB ends. This filament facilitates the search for a homologous donor sequence and promotes strand invasion. Recently caffeine treatment has been shown to prevent gene targeting in mammalian cells by increasing non-productive Rad51 interactions between the DSB and random regions of the genome. Here we show that caffeine treatment prevents gene conversion in yeast, independently of its inhibition of the Mec1ATR/Tel1ATM-dependent DNA damage response or caffeine's inhibition of 5′ to 3′ resection of DSB ends. Caffeine treatment results in a dosage-dependent eviction of Rad51 from ssDNA. Gene conversion is impaired even at low concentrations of caffeine, where there is no discernible dismantling of the Rad51 filament. Loss of the Rad51 filament integrity is independent of Srs2's Rad51 filament dismantling activity or Rad51's ATPase activity and does not depend on non-specific Rad51 binding to undamaged double-stranded DNA. Caffeine treatment had similar effects on irradiated HeLa cells, promoting loss of previously assembled Rad51 foci. We conclude that caffeine treatment can disrupt gene conversion by disrupting Rad51 filaments.
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Affiliation(s)
- Michael Tsabar
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA
| | - Jennifer M Mason
- Department of Radiation and Cellular Oncology and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Yuen-Ling Chan
- Department of Radiation and Cellular Oncology and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Douglas K Bishop
- Department of Radiation and Cellular Oncology and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA
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16
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Liang J, Suhandynata RT, Zhou H. Phosphorylation of Sae2 Mediates Forkhead-associated (FHA) Domain-specific Interaction and Regulates Its DNA Repair Function. J Biol Chem 2015; 290:10751-63. [PMID: 25762720 DOI: 10.1074/jbc.m114.625293] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Indexed: 12/16/2022] Open
Abstract
Saccharomyces cerevisiae Sae2 and its ortholog CtIP in higher eukaryotes have a conserved role in the initial processing of DNA lesions and influencing their subsequent repair pathways. Sae2 is phosphorylated by the ATR/ATM family kinases Mec1 and Tel1 in response to DNA damage. Among the Mec1/Tel1 consensus phosphorylation sites of Sae2, we found that mutations of Thr-90 and Thr-279 of Sae2 into alanine caused a persistent Rad53 activation in response to a transient DNA damage, similar to the loss of Sae2. To gain insight into the function of this phosphorylation of Sae2, we performed a quantitative proteomics analysis to identify its associated proteins. We found that phosphorylation of Thr-90 of Sae2 mediates its interaction with Rad53, Dun1, Xrs2, Dma1, and Dma2, whereas Rad53 and Dun1 additionally interact with phosphorylated Thr-279 of Sae2. Mutations of the ligand-binding residues of Forkhead-associated (FHA) domains of Rad53, Dun1, Xrs2, Dma1, and Dma2 abolished their interactions with Sae2, revealing the involvement of FHA-specific interactions. Mutations of Thr-90 and Thr-279 of Sae2 caused a synergistic defect when combined with sgs1Δ and exo1Δ and elevated gross chromosomal rearrangements. Likewise, mutations of RAD53 and DUN1 caused a synthetic growth defect with sgs1Δ and elevated gross chromosomal rearrangements. These findings suggest that threonine-specific phosphorylation of Sae2 by Mec1 and Tel1 contributes to DNA repair and genome maintenance via its interactions with Rad53 and Dun1.
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Affiliation(s)
- Jason Liang
- From the Ludwig Institute for Cancer Research, Department of Chemistry and Biochemistry
| | | | - Huilin Zhou
- From the Ludwig Institute for Cancer Research, Department of Chemistry and Biochemistry, Department of Cellular and Molecular Medicine, and Moores Cancer Center, University of California at San Diego, La Jolla, California 92093
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17
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Hustedt N, Seeber A, Sack R, Tsai-Pflugfelder M, Bhullar B, Vlaming H, van Leeuwen F, Guénolé A, van Attikum H, Srivas R, Ideker T, Shimada K, Gasser SM. Yeast PP4 interacts with ATR homolog Ddc2-Mec1 and regulates checkpoint signaling. Mol Cell 2015; 57:273-89. [PMID: 25533186 PMCID: PMC5706562 DOI: 10.1016/j.molcel.2014.11.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 10/16/2014] [Accepted: 11/14/2014] [Indexed: 12/25/2022]
Abstract
Mec1-Ddc2 (ATR-ATRIP) controls the DNA damage checkpoint and shows differential cell-cycle regulation in yeast. To find regulators of Mec1-Ddc2, we exploited a mec1 mutant that retains catalytic activity in G2 and recruitment to stalled replication forks, but which is compromised for the intra-S phase checkpoint. Two screens, one for spontaneous survivors and an E-MAP screen for synthetic growth effects, identified loss of PP4 phosphatase, pph3Δ and psy2Δ, as the strongest suppressors of mec1-100 lethality on HU. Restored Rad53 phosphorylation accounts for part, but not all, of the pph3Δ-mediated survival. Phosphoproteomic analysis confirmed that 94% of the mec1-100-compromised targets on HU are PP4 regulated, including a phosphoacceptor site within Mec1 itself, mutation of which confers damage sensitivity. Physical interaction between Pph3 and Mec1, mediated by cofactors Psy2 and Ddc2, is shown biochemically and through FRET in subnuclear repair foci. This establishes a physical and functional Mec1-PP4 unit for regulating the checkpoint response.
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Affiliation(s)
- Nicole Hustedt
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland; Faculty of Sciences, University of Basel, 4056 Basel, Switzerland
| | - Andrew Seeber
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland; Faculty of Sciences, University of Basel, 4056 Basel, Switzerland
| | - Ragna Sack
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Monika Tsai-Pflugfelder
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Bhupinder Bhullar
- Novartis Institutes for Biomedical Research, Novartis Pharma AG, Fabrikstrasse 22, 4056 Basel, Switzerland
| | - Hanneke Vlaming
- Division of Gene Regulation, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - Fred van Leeuwen
- Division of Gene Regulation, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - Aude Guénolé
- Department of Toxicogenetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, the Netherlands
| | - Haico van Attikum
- Department of Toxicogenetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, the Netherlands
| | - Rohith Srivas
- Departments of Bioengineering and Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Trey Ideker
- Departments of Bioengineering and Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kenji Shimada
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland; Faculty of Sciences, University of Basel, 4056 Basel, Switzerland.
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18
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The DNA damage response and checkpoint adaptation in Saccharomyces cerevisiae: distinct roles for the replication protein A2 (Rfa2) N-terminus. Genetics 2015; 199:711-27. [PMID: 25595672 PMCID: PMC4349066 DOI: 10.1534/genetics.114.173211] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In response to DNA damage, two general but fundamental processes occur in the cell: (1) a DNA lesion is recognized and repaired, and (2) concomitantly, the cell halts the cell cycle to provide a window of opportunity for repair to occur. An essential factor for a proper DNA-damage response is the heterotrimeric protein complex Replication Protein A (RPA). Of particular interest is hyperphosphorylation of the 32-kDa subunit, called RPA2, on its serine/threonine-rich amino (N) terminus following DNA damage in human cells. The unstructured N-terminus is often referred to as the phosphorylation domain and is conserved among eukaryotic RPA2 subunits, including Rfa2 in Saccharomyces cerevisiae. An aspartic acid/alanine-scanning and genetic interaction approach was utilized to delineate the importance of this domain in budding yeast. It was determined that the Rfa2 N-terminus is important for a proper DNA-damage response in yeast, although its phosphorylation is not required. Subregions of the Rfa2 N-terminus important for the DNA-damage response were also identified. Finally, an Rfa2 N-terminal hyperphosphorylation-mimetic mutant behaves similarly to another Rfa1 mutant (rfa1-t11) with respect to genetic interactions, DNA-damage sensitivity, and checkpoint adaptation. Our data indicate that post-translational modification of the Rfa2 N-terminus is not required for cells to deal with "repairable" DNA damage; however, post-translational modification of this domain might influence whether cells proceed into M-phase in the continued presence of unrepaired DNA lesions as a "last-resort" mechanism for cell survival.
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19
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Ghospurkar PL, Wilson TM, Liu S, Herauf A, Steffes J, Mueller EN, Oakley GG, Haring SJ. Phosphorylation and cellular function of the human Rpa2 N-terminus in the budding yeast Saccharomyces cerevisiae. Exp Cell Res 2014; 331:183-199. [PMID: 25499885 DOI: 10.1016/j.yexcr.2014.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 11/29/2014] [Accepted: 12/02/2014] [Indexed: 11/18/2022]
Abstract
Maintenance of genome integrity is critical for proper cell growth. This occurs through accurate DNA replication and repair of DNA lesions. A key factor involved in both DNA replication and the DNA damage response is the heterotrimeric single-stranded DNA (ssDNA) binding complex Replication Protein A (RPA). Although the RPA complex appears to be structurally conserved throughout eukaryotes, the primary amino acid sequence of each subunit can vary considerably. Examination of sequence differences along with the functional interchangeability of orthologous RPA subunits or regions could provide insight into important regions and their functions. This might also allow for study in simpler systems. We determined that substitution of yeast Replication Factor A (RFA) with human RPA does not support yeast cell viability. Exchange of a single yeast RFA subunit with the corresponding human RPA subunit does not function due to lack of inter-species subunit interactions. Substitution of yeast Rfa2 with domains/regions of human Rpa2 important for Rpa2 function (i.e., the N-terminus and the loop 3-4 region) supports viability in yeast cells, and hybrid proteins containing human Rpa2 N-terminal phospho-mutations result in similar DNA damage phenotypes to analogous yeast Rfa2 N-terminal phospho-mutants. Finally, the human Rpa2 N-terminus (NT) fused to yeast Rfa2 is phosphorylated in a manner similar to human Rpa2 in human cells, indicating that conserved kinases recognize the human domain in yeast. The implication is that budding yeast represents a potential model system for studying not only human Rpa2 N-terminal phosphorylation, but also phosphorylation of Rpa2 N-termini from other eukaryotic organisms.
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Affiliation(s)
- Padmaja L Ghospurkar
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA
| | - Timothy M Wilson
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA
| | - Shengqin Liu
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| | - Anna Herauf
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA
| | - Jenna Steffes
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA
| | - Erica N Mueller
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA
| | - Gregory G Oakley
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| | - Stuart J Haring
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA; Interdisciplinary Cellular and Molecular Biology Program, North Dakota State University, Fargo, ND 58108, USA.
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20
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Witosch J, Wolf E, Mizuno N. Architecture and ssDNA interaction of the Timeless-Tipin-RPA complex. Nucleic Acids Res 2014; 42:12912-27. [PMID: 25348395 PMCID: PMC4227788 DOI: 10.1093/nar/gku960] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Timeless-Tipin (Tim-Tipin) complex, also referred to as the fork protection complex, is involved in coordination of DNA replication. Tim-Tipin is suggested to be recruited to replication forks via Replication Protein A (RPA) but details of the interaction are unknown. Here, using cryo-EM and biochemical methods, we characterized complex formation of Tim-Tipin, RPA and single-stranded DNA (ssDNA). Tim-Tipin and RPA form a 258 kDa complex with a 1:1:1 stoichiometry. The cryo-EM 3D reconstruction revealed a globular architecture of the Tim-Tipin-RPA complex with a ring-like and a U-shaped domain covered by a RPA lid. Interestingly, RPA in the complex adopts a horse shoe-like shape resembling its conformation in the presence of long ssDNA (>30 nucleotides). Furthermore, the recruitment of the Tim-Tipin-RPA complex to ssDNA is modulated by the RPA conformation and requires RPA to be in the more compact 30 nt ssDNA binding mode. The dynamic formation and disruption of the Tim-Tipin-RPA-ssDNA complex implicates the RPA-based recruitment of Tim-Tipin to the replication fork.
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Affiliation(s)
- Justine Witosch
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Eva Wolf
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany Department of Physiological Chemistry and Center For Integrated Protein Science Munich (CIPSM), Butenandt Institute, Ludwig Maximilians University of Munich, Butenandtstrasse 5, 81377 Munich, Germany Institut für allgemeine Botanik, Johannes Gutenberg-University, Johannes-von-Müller-Weg 6, 55128 Mainz, Germany and Institute of Molecular Biology (IMB), Mainz, Germany
| | - Naoko Mizuno
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
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21
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The C-terminal residues of Saccharomyces cerevisiae Mec1 are required for its localization, stability, and function. G3-GENES GENOMES GENETICS 2013; 3:1661-74. [PMID: 23934994 PMCID: PMC3789791 DOI: 10.1534/g3.113.006841] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Mec1, a member of the phosphoinositide three-kinase-related kinase (PIKK) family of proteins, is involved in the response to replicative stress and DNA damage and in telomere maintenance. An essential 30 to 35 residue, the FATC domain is found at the C-terminus of all PIKK family members. To investigate the roles of the C-terminal residues of Mec1, we characterized alleles of Saccharomyces cerevisiae mec1 that alter the FATC domain. A change of the terminal tryptophan to alanine resulted in temperature-sensitive growth, sensitivity to hydroxyurea, and diminished kinase activity in vitro. Addition of a terminal glycine or deletion of one, two, or three residues resulted in loss of cell viability and kinase function. Each of these Mec1 derivatives was less stable than wild-type Mec1, eluted abnormally from a size exclusion column, and showed reduced nuclear localization. We identified rpn3-L140P, which encodes a component of the 19S proteasomal regulatory particle of the 26S proteasome, as a suppressor of the temperature-sensitive growth caused by mec1-W2368A. The rpn3-L140P allele acted in a partially dominant fashion. It was not able to suppress the inviability of the C-terminal truncations or additions or the hydroxyurea sensitivity of mec1-W2368A. The rpn3-L140P allele restored Mec1-W2368A to nearly wild-type protein levels at 37°, an effect partially mimicked by the proteasome inhibitor MG-132. Our study supports a role for the C-terminus in Mec1 folding and stability, and suggests a role for the proteasome in regulating Mec1 levels.
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22
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Replication checkpoint: tuning and coordination of replication forks in s phase. Genes (Basel) 2013; 4:388-434. [PMID: 24705211 PMCID: PMC3924824 DOI: 10.3390/genes4030388] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 07/30/2013] [Accepted: 08/02/2013] [Indexed: 12/01/2022] Open
Abstract
Checkpoints monitor critical cell cycle events such as chromosome duplication and segregation. They are highly conserved mechanisms that prevent progression into the next phase of the cell cycle when cells are unable to accomplish the previous event properly. During S phase, cells also provide a surveillance mechanism called the DNA replication checkpoint, which consists of a conserved kinase cascade that is provoked by insults that block or slow down replication forks. The DNA replication checkpoint is crucial for maintaining genome stability, because replication forks become vulnerable to collapse when they encounter obstacles such as nucleotide adducts, nicks, RNA-DNA hybrids, or stable protein-DNA complexes. These can be exogenously induced or can arise from endogenous cellular activity. Here, we summarize the initiation and transduction of the replication checkpoint as well as its targets, which coordinate cell cycle events and DNA replication fork stability.
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23
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Bryan C, Rice C, Harkisheimer M, Schultz DC, Skordalakes E. Structure of the human telomeric Stn1-Ten1 capping complex. PLoS One 2013; 8:e66756. [PMID: 23826127 PMCID: PMC3691326 DOI: 10.1371/journal.pone.0066756] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 05/10/2013] [Indexed: 12/03/2022] Open
Abstract
The identification of the human homologue of the yeast CST in 2009 posed a new challenge in our understanding of the mechanism of telomere capping in higher eukaryotes. The high-resolution structure of the human Stn1-Ten1 (hStn1-Ten1) complex presented here reveals that hStn1 consists of an OB domain and tandem C-terminal wHTH motifs, while hTen1 consists of a single OB fold. Contacts between the OB domains facilitate formation of a complex that is strikingly similar to the replication protein A (RPA) and yeast Stn1-Ten1 (Ten1) complexes. The hStn1-Ten1 complex exhibits non-specific single-stranded DNA activity that is primarily dependent on hStn1. Cells expressing hStn1 mutants defective for dimerization with hTen1 display elongated telomeres and telomere defects associated with telomere uncapping, suggesting that the telomeric function of hCST is hTen1 dependent. Taken together the data presented here show that the structure of the hStn1-Ten1 subcomplex is conserved across species. Cell based assays indicate that hTen1 is critical for the telomeric function of hCST, both in telomere protection and downregulation of telomerase function.
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Affiliation(s)
- Christopher Bryan
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Cory Rice
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Michael Harkisheimer
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - David C. Schultz
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Emmanuel Skordalakes
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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24
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Le PN, Maranon DG, Altina NH, Battaglia CLR, Bailey SM. TERRA, hnRNP A1, and DNA-PKcs Interactions at Human Telomeres. Front Oncol 2013; 3:91. [PMID: 23616949 PMCID: PMC3628365 DOI: 10.3389/fonc.2013.00091] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 04/04/2013] [Indexed: 01/29/2023] Open
Abstract
Maintenance of telomeres, repetitive elements at eukaryotic chromosomal termini, and the end-capping structure and function they provide, are imperative for preserving genome integrity and stability. The discovery that telomeres are transcribed into telomere repeat containing RNA (TERRA) has revolutionized our view of this repetitive, rather unappreciated region of the genome. We have previously shown that the non-homologous end-joining, shelterin associated DNA dependent protein kinase catalytic subunit (DNA-PKcs) participates in mammalian telomeric end-capping, exclusively at telomeres created by leading-strand synthesis. Here, we explore potential roles of DNA-PKcs and its phosphorylation target heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) in the localization of TERRA at human telomeres. Evaluation of co-localized foci utilizing RNA-FISH and three-dimensional (3D) reconstruction strategies provided evidence that both inhibition of DNA-PKcs kinase activity and siRNA depletion of hnRNP A1 result in accumulation of TERRA at individual telomeres; depletion of hnRNP A1 also resulted in increased frequencies of fragile telomeres. These observations are consistent with previous demonstrations that decreased levels of the nonsense RNA-mediated decay factors SMG1 and UPF1 increase TERRA at telomeres and interfere with replication of leading-strand telomeres. We propose that hTR mediated stimulation of DNA-PKcs and subsequent phosphorylation of hnRNP A1 influences the cell cycle dependent distribution of TERRA at telomeres by contributing to the removal of TERRA from telomeres, an action important for progression of S-phase, and thereby facilitating efficient telomere replication and end-capping.
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Affiliation(s)
- Phuong N Le
- Department of Environmental and Radiological Health Sciences, Colorado State University Fort Collins, CO, USA
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25
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Abstract
The yeast Mec1 kinase is a key regulator of the DNA damage response (DDR). In this issue of Genes & Development, Kumar and Burgers (pp. 313-321) report that Ddc1, Dpb11, and Dna2 function in concert to activate Mec1 during S phase of the cell cycle. Furthermore, the Tel1 kinase also contributes to the DDR in S phase when Mec1 activation is compromised.
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Affiliation(s)
- Lee Zou
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
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26
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Abstract
Rfa2 is a ssDNA (single-stranded DNA)-binding protein that plays an important role in DNA replication, recombination and repair. Rfa2 is regulated by phosphorylation, which alters its protein–protein interaction and protein–DNA interaction. In the present study, we found that the Pph3–Psy2 phosphatase complex is responsible for Rfa2 dephosphorylation both during normal G1-phase and under DNA replication stress in Candida albicans. Phosphorylated Rfa2 extracted from pph3Δ or psy2Δ G1 cells exhibited diminished binding affinity to dsDNA (double-stranded DNA) but not to ssDNA. We also discovered that Cdc28 (cell division cycle 28) and Mec1 are responsible for Rfa2 phosphorylation in G1-phase and under DNA replication stress respectively. Moreover, MS revealed that the domain of Rfa2 that was phosphorylated in G1-phase differed from that phosphorylated under the stress conditions. The results of the present study imply that differential phosphorylation plays a crucial role in RPA (replication protein A) regulation.
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27
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An N-terminal acidic region of Sgs1 interacts with Rpa70 and recruits Rad53 kinase to stalled forks. EMBO J 2012; 31:3768-83. [PMID: 22820947 DOI: 10.1038/emboj.2012.195] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 06/28/2012] [Indexed: 11/08/2022] Open
Abstract
DNA replication fork stalling poses a major threat to genome stability. This is counteracted in part by the intra-S phase checkpoint, which stabilizes arrested replication machinery, prevents cell-cycle progression and promotes DNA repair. The checkpoint kinase Mec1/ATR and RecQ helicase Sgs1/BLM contribute synergistically to fork maintenance on hydroxyurea (HU). Both enzymes interact with replication protein A (RPA). We identified and deleted the major interaction sites on Sgs1 for Rpa70, generating a mutant called sgs1-r1. In contrast to a helicase-dead mutant of Sgs1, sgs1-r1 did not significantly reduce recovery of DNA polymerase α at HU-arrested replication forks. However, the Sgs1 R1 domain is a target of Mec1 kinase, deletion of which compromises Rad53 activation on HU. Full activation of Rad53 is achieved through phosphorylation of the Sgs1 R1 domain by Mec1, which promotes Sgs1 binding to the FHA1 domain of Rad53 with high affinity. We propose that the recruitment of Rad53 by phosphorylated Sgs1 promotes the replication checkpoint response on HU. Loss of the R1 domain increases lethality selectively in cells lacking Mus81, Slx4, Slx5 or Slx8.
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Finn K, Lowndes NF, Grenon M. Eukaryotic DNA damage checkpoint activation in response to double-strand breaks. Cell Mol Life Sci 2012; 69:1447-73. [PMID: 22083606 PMCID: PMC11115150 DOI: 10.1007/s00018-011-0875-3] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 10/19/2011] [Accepted: 10/20/2011] [Indexed: 02/07/2023]
Abstract
Double-strand breaks (DSBs) are the most detrimental form of DNA damage. Failure to repair these cytotoxic lesions can result in genome rearrangements conducive to the development of many diseases, including cancer. The DNA damage response (DDR) ensures the rapid detection and repair of DSBs in order to maintain genome integrity. Central to the DDR are the DNA damage checkpoints. When activated by DNA damage, these sophisticated surveillance mechanisms induce transient cell cycle arrests, allowing sufficient time for DNA repair. Since the term "checkpoint" was coined over 20 years ago, our understanding of the molecular mechanisms governing the DNA damage checkpoint has advanced significantly. These pathways are highly conserved from yeast to humans. Thus, significant findings in yeast may be extrapolated to vertebrates, greatly facilitating the molecular dissection of these complex regulatory networks. This review focuses on the cellular response to DSBs in Saccharomyces cerevisiae, providing a comprehensive overview of how these signalling pathways function to orchestrate the cellular response to DNA damage and preserve genome stability in eukaryotic cells.
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Affiliation(s)
- Karen Finn
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
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29
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Errico A, Costanzo V. Mechanisms of replication fork protection: a safeguard for genome stability. Crit Rev Biochem Mol Biol 2012; 47:222-35. [DOI: 10.3109/10409238.2012.655374] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Abstract
Telomeres are essential for the stability and complete replication of linear chromosomes. Telomere elongation by telomerase counteracts the telomere shortening due to the incomplete replication of chromosome ends by DNA polymerase. Telomere elongation is cell-cycle-regulated and coupled to DNA replication during S-phase. However, the molecular mechanisms that underlie such cell-cycle-dependent telomere elongation by telomerase remain largely unknown. Several aspects of telomere replication in budding yeast, including the modulation of telomere chromatin structure, telomere end processing, recruitment of telomere-binding proteins and telomerase complex to telomere as well as the coupling of DNA replication to telomere elongation during cell cycle progression will be discussed, and the potential roles of Cdk (cyclin-dependent kinase) in these processes will be illustrated.
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32
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Wagner JM, Kaufmann SH. Prospects for the Use of ATR Inhibitors to Treat Cancer. Pharmaceuticals (Basel) 2010; 3:1311-1334. [PMID: 27713304 PMCID: PMC4033983 DOI: 10.3390/ph3051311] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 04/12/2010] [Accepted: 04/19/2010] [Indexed: 01/08/2023] Open
Abstract
ATR is an apical kinase in one of the DNA-damage induced checkpoint pathways. Despite the development of inhibitors of kinases structurally related to ATR, as well as inhibitors of the ATR substrate Chk1, no ATR inhibitors have yet been developed. Here we review the effects of ATR downregulation in cancer cells and discuss the potential for development of ATR inhibitors for clinical use.
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Affiliation(s)
- Jill M Wagner
- Division of Oncology Research, College of Medicine, Mayo Clinic, 200 First St., S.W., Rochester, MN 55905, USA.
| | - Scott H Kaufmann
- Division of Oncology Research, College of Medicine, Mayo Clinic, 200 First St., S.W., Rochester, MN 55905, USA.
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Chen SH, Albuquerque CP, Liang J, Suhandynata RT, Zhou H. A proteome-wide analysis of kinase-substrate network in the DNA damage response. J Biol Chem 2010; 285:12803-12. [PMID: 20190278 DOI: 10.1074/jbc.m110.106989] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The DNA damage checkpoint, consisting of an evolutionarily conserved protein kinase cascade, controls the DNA damage response in eukaryotes. Knowledge of the in vivo substrates of the checkpoint kinases is essential toward understanding their functions. Here we used quantitative mass spectrometry to identify 53 new and 34 previously known targets of Mec1/Tel1, Rad53, and Dun1 in Saccharomyces cerevisiae. Analysis of replication protein A (RPA)-associated proteins reveals extensive physical interactions between RPA-associated proteins and Mec1/Tel1-specific substrates. Among them, multiple subunits of the chromatin remodeling complexes including ISW1, ISW2, INO80, SWR1, RSC, and SWI/SNF are identified and they undergo DNA damage-induced phosphorylation by Mec1 and Tel1. Taken together, this study greatly expands the existing knowledge of the targets of DNA damage checkpoint kinases and provides insights into the role of RPA-associated chromatins in mediating Mec1 and Tel1 substrate phosphorylation in vivo.
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Affiliation(s)
- Sheng-hong Chen
- Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, California 92093-0653, USA
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34
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Janke R, Herzberg K, Rolfsmeier M, Mar J, Bashkirov VI, Haghnazari E, Cantin G, Yates JR, Heyer WD. A truncated DNA-damage-signaling response is activated after DSB formation in the G1 phase of Saccharomyces cerevisiae. Nucleic Acids Res 2010; 38:2302-13. [PMID: 20061370 PMCID: PMC2853130 DOI: 10.1093/nar/gkp1222] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In Saccharomyces cerevisiae, the DNA damage response (DDR) is activated by the spatio-temporal colocalization of Mec1-Ddc2 kinase and the 9-1-1 clamp. In the absence of direct means to monitor Mec1 kinase activation in vivo, activation of the checkpoint kinase Rad53 has been taken as a proxy for DDR activation. Here, we identify serine 378 of the Rad55 recombination protein as a direct target site of Mec1. Rad55-S378 phosphorylation leads to an electrophoretic mobility shift of the protein and acts as a sentinel for Mec1 activation in vivo. A single double-stranded break (DSB) in G1-arrested cells causes phosphorylation of Rad55-S378, indicating activation of Mec1 kinase. However, Rad53 kinase is not detectably activated under these conditions. This response required Mec1-Ddc2 and loading of the 9-1-1 clamp by Rad24-RFC, but not Rad9 or Mrc1. In addition to Rad55–S378, two additional direct Mec1 kinase targets are phosphorylated, the middle subunit of the ssDNA-binding protein RPA, RPA2 and histone H2A (H2AX). These data suggest the existence of a truncated signaling pathway in response to a single DSB in G1-arrested cells that activates Mec1 without eliciting a full DDR involving the entire signaling pathway including the effector kinases.
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Affiliation(s)
- Ryan Janke
- Department of Microbiology, University of California, Davis, CA 95616-8665, USA
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35
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Pandita TK, Richardson C. Chromatin remodeling finds its place in the DNA double-strand break response. Nucleic Acids Res 2009; 37:1363-77. [PMID: 19139074 PMCID: PMC2655678 DOI: 10.1093/nar/gkn1071] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 12/20/2008] [Indexed: 12/16/2022] Open
Abstract
The accurate repair of chromosomal double-strand breaks (DSBs) arising from exposure to exogenous agents, such as ionizing radiation (IR) and radiomimetic drugs is crucial in maintaining genomic integrity, cellular viability and the prevention of tumorigenesis. Eukaryotic cells have evolved efficient mechanisms that sense and respond to DSBs. The DNA DSB response is facilitated by hierarchical signaling networks that orchestrate chromatin structural changes, cell-cycle checkpoints and multiple enzymatic activities to repair the broken DNA ends. Sensors and transducers signal to numerous downstream cellular effectors which function primarily by substrate posttranslational modifications including phosphorylation, acetylation, methylation and ubiquitylation. In particular, the past several years have provided important insight into the role of chromatin remodeling and histones-specific modifications to control DNA damage detection, signaling and repair. This review summarizes recently identified factors that influence this complex process and the repair of DNA DSBs in eukaryotic cells.
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Affiliation(s)
- Tej K Pandita
- Department of Radiation Oncology, Washington University School of Medicine, St Louis, MO 63108, USA.
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36
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Alabert C, Bianco JN, Pasero P. Differential regulation of homologous recombination at DNA breaks and replication forks by the Mrc1 branch of the S-phase checkpoint. EMBO J 2009; 28:1131-41. [PMID: 19322196 DOI: 10.1038/emboj.2009.75] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Accepted: 03/04/2009] [Indexed: 11/09/2022] Open
Abstract
The Rad52 pathway has a central function in the recombinational repair of chromosome breaks and in the recovery from replication stress. Tolerance to replication stress also depends on the Mec1 kinase, which activates the DNA replication checkpoint in an Mrc1-dependent manner in response to fork arrest. Although the Mec1 and Rad52 pathways are initiated by the same single-strand DNA (ssDNA) intermediate, their interplay at stalled forks remains largely unexplored. Here, we show that the replication checkpoint suppresses the formation of Rad52 foci in an Mrc1-dependent manner and prevents homologous recombination (HR) at chromosome breaks induced by the HO endonuclease. This repression operates at least in part by impeding resection of DNA ends, which is essential to generate 3' ssDNA tails, the primary substrate of HR. Interestingly, we also observed that the Mec1 pathway does not prevent recombination at stalled forks, presumably because they already contain ssDNA. Taken together, these data indicate that the DNA replication checkpoint suppresses genomic instability in S phase by blocking recombination at chromosome breaks and permitting helpful recombination at stalled forks.
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Affiliation(s)
- Constance Alabert
- Department of Genome Dynamics, Institute of Human Genetics, CNRS UPR 1142, Montpellier, France
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37
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Barlow JH, Rothstein R. Rad52 recruitment is DNA replication independent and regulated by Cdc28 and the Mec1 kinase. EMBO J 2009; 28:1121-30. [PMID: 19262568 DOI: 10.1038/emboj.2009.43] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 01/19/2009] [Indexed: 11/09/2022] Open
Abstract
Recruitment of the homologous recombination machinery to sites of double-strand breaks is a cell cycle-regulated event requiring entry into S phase and CDK1 activity. Here, we demonstrate that the central recombination protein, Rad52, forms foci independent of DNA replication, and its recruitment requires B-type cyclin/CDK1 activity. Induction of the intra-S-phase checkpoint by hydroxyurea (HU) inhibits Rad52 focus formation in response to ionizing radiation. This inhibition is dependent upon Mec1/Tel1 kinase activity, as HU-treated cells form Rad52 foci in the presence of the PI3 kinase inhibitor caffeine. These Rad52 foci colocalize with foci formed by the replication clamp PCNA. These results indicate that Mec1 activity inhibits the recruitment of Rad52 to both sites of DNA damage and stalled replication forks during the intra-S-phase checkpoint. We propose that B-type cyclins promote the recruitment of Rad52 to sites of DNA damage, whereas Mec1 inhibits spurious recombination at stalled replication forks.
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Affiliation(s)
- Jacqueline H Barlow
- Department of Genetics & Development, Columbia University Medical Center, New York, NY 10032-2704, USA
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38
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Li S, Makovets S, Matsuguchi T, Blethrow JD, Shokat KM, Blackburn EH. Cdk1-dependent phosphorylation of Cdc13 coordinates telomere elongation during cell-cycle progression. Cell 2009; 136:50-61. [PMID: 19135888 DOI: 10.1016/j.cell.2008.11.027] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Revised: 09/11/2008] [Accepted: 11/20/2008] [Indexed: 10/21/2022]
Abstract
Elongation of telomeres by telomerase replenishes the loss of terminal telomeric DNA repeats during each cell cycle. In budding yeast, Cdc13 plays an essential role in telomere length homeostasis, partly through its interactions with both the telomerase complex and the competing Stn1-Ten1 complex. Previous studies in yeast have shown that telomere elongation by telomerase is cell cycle dependent, but the mechanism underlying this dependence is unclear. In S. cerevisiae, a single cyclin-dependent kinase Cdk1 (Cdc28) coordinates the serial events required for the cell division cycle, but no Cdk1 substrate has been identified among telomerase and telomere-associated factors. Here we show that Cdk1-dependent phosphorylation of Cdc13 is essential for efficient recruitment of the yeast telomerase complex to telomeres by favoring the interaction of Cdc13 with Est1 rather than the competing Stn1-Ten1 complex. These results provide a direct mechanistic link between coordination of telomere elongation and cell-cycle progression in vivo.
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Affiliation(s)
- Shang Li
- Department of Biochemistry and Biophysics, University of California, San Francisco, Box 2200, San Francisco, CA 94143-2200, USA
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39
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Koltovaya NA. Activation of repair and checkpoints by double-strand DNA breaks: Activational cascade of protein phosphorylation. RUSS J GENET+ 2009. [DOI: 10.1134/s1022795409010013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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40
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Cimprich KA, Cortez D. ATR: an essential regulator of genome integrity. Nat Rev Mol Cell Biol 2008; 9:616-27. [PMID: 18594563 DOI: 10.1038/nrm2450] [Citation(s) in RCA: 1301] [Impact Index Per Article: 81.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Genome maintenance is a constant concern for cells, and a coordinated response to DNA damage is required to maintain cellular viability and prevent disease. The ataxia-telangiectasia mutated (ATM) and ATM and RAD3-related (ATR) protein kinases act as master regulators of the DNA-damage response by signalling to control cell-cycle transitions, DNA replication, DNA repair and apoptosis. Recent studies have provided new insights into the mechanisms that control ATR activation, have helped to explain the overlapping but non-redundant activities of ATR and ATM in DNA-damage signalling, and have clarified the crucial functions of ATR in maintaining genome integrity.
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Affiliation(s)
- Karlene A Cimprich
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Clark Center, 318 Campus Drive, W350B, Stanford, California 94305-5441, USA.
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41
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Alvino GM, Collingwood D, Murphy JM, Delrow J, Brewer BJ, Raghuraman MK. Replication in hydroxyurea: it's a matter of time. Mol Cell Biol 2007; 27:6396-406. [PMID: 17636020 PMCID: PMC2099622 DOI: 10.1128/mcb.00719-07] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Hydroxyurea (HU) is a DNA replication inhibitor that negatively affects both the elongation and initiation phases of replication and triggers the "intra-S phase checkpoint." Previous work with budding yeast has shown that, during a short exposure to HU, MEC1/RAD53 prevent initiation at some late S phase origins. In this study, we have performed microarray experiments to follow the fate of all origins over an extended exposure to HU. We show that the genome-wide progression of DNA synthesis, including origin activation, follows the same pattern in the presence of HU as in its absence, although the time frames are very different. We find no evidence for a specific effect that excludes initiation from late origins. Rather, HU causes S phase to proceed in slow motion; all temporal classes of origins are affected, but the order in which they become active is maintained. We propose a revised model for the checkpoint response to HU that accounts for the continued but slowed pace of the temporal program of origin activation.
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Affiliation(s)
- Gina M Alvino
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
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42
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Smolka MB, Albuquerque CP, Chen SH, Zhou H. Proteome-wide identification of in vivo targets of DNA damage checkpoint kinases. Proc Natl Acad Sci U S A 2007; 104:10364-9. [PMID: 17563356 PMCID: PMC1965519 DOI: 10.1073/pnas.0701622104] [Citation(s) in RCA: 327] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Understanding the role of DNA damage checkpoint kinases in the cellular response to genotoxic stress requires the knowledge of their substrates. Here, we report the use of quantitative phosphoproteomics to identify in vivo kinase substrates of the yeast DNA damage checkpoint kinases Mec1, Tel1, and Rad53 (orthologs of human ATR, ATM, and CHK2, respectively). By analyzing 2,689 phosphorylation sites in wild-type and various kinase-null cells, 62 phosphorylation sites from 55 proteins were found to be controlled by the DNA damage checkpoint. Examination of the dependency of each phosphorylation on Mec1 and Tel1 or Rad53, combined with sequence and biochemical analysis, revealed that many of the identified targets are likely direct substrates of these kinases. In addition to several known targets, 50 previously undescribed targets of the DNA damage checkpoint were identified, suggesting that a wide range of cellular processes is likely regulated by Mec1, Tel1, and Rad53.
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Affiliation(s)
- Marcus B. Smolka
- *Ludwig Institute for Cancer Research, La Jolla, CA 92093-0653; and
| | - Claudio P. Albuquerque
- *Ludwig Institute for Cancer Research, La Jolla, CA 92093-0653; and
- Departments of Chemistry and Biochemistry and
| | - Sheng-hong Chen
- *Ludwig Institute for Cancer Research, La Jolla, CA 92093-0653; and
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0653
| | - Huilin Zhou
- *Ludwig Institute for Cancer Research, La Jolla, CA 92093-0653; and
- Cellular and Molecular Medicine and
- To whom correspondence should be addressed. E-mail:
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43
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Majka J, Niedziela-Majka A, Burgers PMJ. The checkpoint clamp activates Mec1 kinase during initiation of the DNA damage checkpoint. Mol Cell 2007; 24:891-901. [PMID: 17189191 PMCID: PMC1850967 DOI: 10.1016/j.molcel.2006.11.027] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 11/17/2006] [Accepted: 11/30/2006] [Indexed: 11/22/2022]
Abstract
Yeast Mec1/Ddc2 protein kinase, the ortholog of human ATR/ATRIP, plays a central role in the DNA damage checkpoint. The PCNA-like clamp Rad17/Mec3/Ddc1 (the 9-1-1 complex in human) and its loader Rad24-RFC are also essential components of this signal transduction pathway. Here we have studied the role of the clamp in regulating Mec1, and we delineate how the signal generated by DNA lesions is transduced to the Rad53 effector kinase. The checkpoint clamp greatly activates the kinase activity of Mec1, but only if the clamp is appropriately loaded upon partial duplex DNA. Activated Mec1 phosphorylates the Ddc1 and Mec3 subunits of the clamp, the Rad24 subunit of the loader, and the Rpa1 and Rpa2 subunits of RPA. Phosphorylation of Rad53, and of human PHAS-1, a nonspecific target, also requires a properly loaded clamp. Phosphorylation and binding studies with individual clamp subunits indicate that the Ddc1 subunit mediates the functional interactions with Mec1.
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44
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Abstract
In Saccharomyces cerevisiae, H3 methylation at lysine 4 (H3K4) is mediated by Set1. Set1 is a large protein bearing a conserved RNA recognition motif in addition to its catalytic C-terminal SET domain. The SET and RRM domains are conserved in Set1 orthologs from yeast to humans. Set1 belongs to a complex of 8 proteins, also showing a striking conservation, most subunits being required to efficiently catalyze methylation of H3K4. The deletion of SET1 is not lethal but has pleiotropic phenotypes. It affects growth, transcriptional activation, repression and elongation, telomere length regulation, telomeric position effect, rDNA silencing, meiotic differentiation, DNA repair, chromosome segregation, and cell wall organization. In this review, we discuss the regulation of H3K4 methylation and try to link Set1 activity with the multiple phenotypes displayed by cells lacking Set1. We also suggest that Set1 may have multiple targets.
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Affiliation(s)
- Pierre-Marie Dehé
- Instabilité du Génome et Cancerogénèse (IGC), CNRS, 31 chemin Joseph Aiguier, 13402 Marseille, cedex 20, France
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45
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Abstract
DNA double-strand breaks (DSBs) are the most hazardous lesions arising in the genome of eukaryotic organisms, and yet occur normally during DNA replication, meiosis, and immune system development. The efficient repair of DSBs is crucial in maintaining genomic integrity, cellular viability, and the prevention of tumorigenesis. As a consequence, eukaryotic cells have evolved efficient mechanisms that sense and respond to DSBs and ultimately repair the break. The swiftness of the DNA DSB response has paved to the identification of sensors and transducers which allowed to generate a hierarchical signaling paradigm depicting the transduction of the damage signal to numerous downstream effectors (Fig. 1). The function of such effectors involve posttranslational modifications through phosphorylation, acetylation, and methylation of the substrates. This review will address the control of DSBs in damaged eukaryotic cells, the physiological processes that require the introduction of a DSB into the genome, and the maintenance of DSBs in non-damaged cells.
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Affiliation(s)
- Shaun P Scott
- Department of Radiation Oncology, Washington University School of Medicine, 4511 Forest Park, St. Louis, MO 63108, USA
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46
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Sawarynski KE, Kaplun A, Tzivion G, Brush GS. Distinct activities of the related protein kinases Cdk1 and Ime2. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1773:450-6. [PMID: 17137646 PMCID: PMC3814016 DOI: 10.1016/j.bbamcr.2006.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Revised: 10/09/2006] [Accepted: 10/11/2006] [Indexed: 11/29/2022]
Abstract
In budding yeast, commitment to DNA replication during the normal cell cycle requires degradation of the cyclin-dependent kinase (CDK) inhibitor Sic1. The G1 cyclin-CDK complexes Cln1-Cdk1 and Cln2-Cdk1 initiate the process of Sic1 removal by directly catalyzing Sic1 phosphorylation at multiple sites. Commitment to DNA replication during meiosis also appears to require Sic1 degradation, but the G1 cyclin-CDK complexes are not involved. It has been proposed that the meiosis-specific protein kinase Ime2 functionally replaces the G1 cyclin-CDK complexes to promote Sic1 destruction. To investigate this possibility, we compared Cln2-Cdk1 and Ime2 protein kinase activities in vitro. Both enzyme preparations were capable of catalyzing phosphorylation of a GST-Sic1 fusion protein, but the phosphoisomers generated by the two activities had significantly different electrophoretic mobilities. Furthermore, mutation of consensus CDK phosphorylation sites in Sic1 affected Cln2-Cdk1- but not Ime2-dependent phosphorylation. Phosphoamino acid analysis and phosphopeptide mapping provided additional evidence that Cln2-Cdk1 and Ime2 targeted different residues within Sic1. Examination of other substrates both in vitro and in vivo also revealed differing specificities. These results indicate that Ime2 does not simply replace G1 cyclin-CDK complexes in promoting Sic1 degradation during meiosis.
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Affiliation(s)
| | | | | | - George S. Brush
- Corresponding author: George S. Brush, Karmanos Cancer Institute, 3114 Prentis Center, 110 E. Warren Ave., Detroit, MI 48201; Tel, 313-833-0715; Fax, 313-832-7294; Email,
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47
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Olson E, Nievera CJ, Klimovich V, Fanning E, Wu X. RPA2 is a direct downstream target for ATR to regulate the S-phase checkpoint. J Biol Chem 2006; 281:39517-33. [PMID: 17035231 DOI: 10.1074/jbc.m605121200] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Upon DNA damage, replication is inhibited by the S-phase checkpoint. ATR (ataxia telangiectasia mutated- and Rad3-related) is specifically involved in the inhibition of replicon initiation when cells are treated with DNA damage-inducing agents that stall replication forks, but the mechanism by which it acts to prevent replication is not yet fully understood. We observed that RPA2 is phosphorylated on chromatin in an ATR-dependent manner when replication forks are stalled. Mutation of the ATR-dependent phosphorylation sites in RPA2 leads to a defect in the down-regulation of DNA synthesis following treatment with UV radiation, although ATR activation is not affected. Threonine 21 and serine 33, two residues among several phosphorylation sites in the amino terminus of RPA2, are specifically required for the UV-induced, ATR-mediated inhibition of DNA replication. RPA2 mutant alleles containing phospho-mimetic mutations at ATR-dependent phosphorylation sites have an impaired ability to associate with replication centers, indicating that ATR phosphorylation of RPA2 directly affects the replication function of RPA. Our studies suggest that in response to UV-induced DNA damage, ATR rapidly phosphorylates RPA2, disrupting its association with replication centers in the S-phase and contributing to the inhibition of DNA replication.
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Affiliation(s)
- Erin Olson
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La, Jolla, California 92037, USA
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48
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Guo S, Zhang Y, Yuan F, Gao Y, Gu L, Wong I, Li GM. Regulation of replication protein A functions in DNA mismatch repair by phosphorylation. J Biol Chem 2006; 281:21607-21616. [PMID: 16731533 DOI: 10.1074/jbc.m603504200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Replication protein A (RPA) is involved in multiple stages of DNA mismatch repair (MMR); however, the modulation of its functions between different stages is unknown. We show here that phosphorylation likely modulates RPA functions during MMR. Unphosphorylated RPA initially binds to nicked heteroduplex DNA to facilitate assembly of the MMR initiation complex. The unphosphorylated protein preferentially stimulates mismatch-provoked excision, possibly by cooperatively binding to the resultant single-stranded DNA gap. The DNA-bound RPA begins to be phosphorylated after extensive excision, resulting in severalfold reduction in the DNA binding affinity of RPA. Thus, during the phase of repair DNA synthesis, the phosphorylated RPA readily disassociates from DNA, making the DNA template available for DNA polymerase delta-catalyzed resynthesis. These observations support a model of how phosphorylation alters the DNA binding affinity of RPA to fulfill its differential requirement at the various stages of MMR.
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Affiliation(s)
- Shuangli Guo
- Department of Molecular & Cellular Biochemistry and Markey Cancer Center, University of Kentucky Medical Center, Lexington, Kentucky 40536
| | - Yanbin Zhang
- Graduate Center for Toxicology and Department of Pathology, University of Kentucky Medical Center, Lexington, Kentucky 40536
| | - Fenghua Yuan
- Graduate Center for Toxicology and Department of Pathology, University of Kentucky Medical Center, Lexington, Kentucky 40536
| | - Yin Gao
- Graduate Center for Toxicology and Department of Pathology, University of Kentucky Medical Center, Lexington, Kentucky 40536
| | - Liya Gu
- Graduate Center for Toxicology and Department of Pathology, University of Kentucky Medical Center, Lexington, Kentucky 40536
| | - Isaac Wong
- Department of Molecular & Cellular Biochemistry and Markey Cancer Center, University of Kentucky Medical Center, Lexington, Kentucky 40536
| | - Guo-Min Li
- Department of Molecular & Cellular Biochemistry and Markey Cancer Center, University of Kentucky Medical Center, Lexington, Kentucky 40536; Graduate Center for Toxicology and Department of Pathology, University of Kentucky Medical Center, Lexington, Kentucky 40536.
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Rossi ML, Purohit V, Brandt PD, Bambara RA. Lagging strand replication proteins in genome stability and DNA repair. Chem Rev 2006; 106:453-73. [PMID: 16464014 DOI: 10.1021/cr040497l] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Marie L Rossi
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, New York 14642, USA
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Tak YS, Tanaka Y, Endo S, Kamimura Y, Araki H. A CDK-catalysed regulatory phosphorylation for formation of the DNA replication complex Sld2-Dpb11. EMBO J 2006; 25:1987-96. [PMID: 16619031 PMCID: PMC1456926 DOI: 10.1038/sj.emboj.7601075] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Accepted: 03/09/2006] [Indexed: 11/09/2022] Open
Abstract
Phosphorylation often regulates protein-protein interactions to control biological reactions. The Sld2 and Dpb11 proteins of budding yeast form a phosphorylation-dependent complex that is essential for chromosomal DNA replication. The Sld2 protein has a cluster of 11 cyclin-dependent kinase (CDK) phosphorylation motifs (Ser/Thr-Pro), six of which match the canonical sequences Ser/Thr-Pro-X-Lys/Arg, Lys/Arg-Ser/Thr-Pro and Ser/Thr-Pro-Lys/Arg. Simultaneous alanine substitution for serine or threonine in all the canonical CDK-phosphorylation motifs severely reduces complex formation between Sld2 and Dpb11, and inhibits DNA replication. Here we show that phosphorylation of these canonical motifs does not play a direct role in complex formation, but rather regulates phosphorylation of another residue, Thr84. This constitutes a non-canonical CDK-phosphorylation motif within a 28-amino-acid sequence that is responsible, after phosphorylation, for binding of Sld2-Dpb11. We further suggest that CDK-catalysed phosphorylation of sites other than Thr84 renders Thr84 accessible to CDK. Finally, we argue that this novel mechanism sets a threshold of CDK activity for formation of the essential Sld2 to Dpb11 complex and therefore prevents premature DNA replication.
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Affiliation(s)
- Yon-Soo Tak
- Division of Microbial Genetics, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
- Department of Genetics, SOKENDAI, Mishima, Shizuoka, Japan
| | - Yoshimi Tanaka
- Division of Microbial Genetics, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
- CREST, Kawaguchi, Saitama, Japan
| | - Shizuko Endo
- Division of Microbial Genetics, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
| | - Yoichiro Kamimura
- Division of Microbial Genetics, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
- Department of Genetics, SOKENDAI, Mishima, Shizuoka, Japan
- CREST, Kawaguchi, Saitama, Japan
| | - Hiroyuki Araki
- Division of Microbial Genetics, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
- Department of Genetics, SOKENDAI, Mishima, Shizuoka, Japan
- CREST, Kawaguchi, Saitama, Japan
- Division of Microbial Genetics, National Institute of Genetics, Research Organization of Information and Systems, Yata 1111, Mishima, Shizuoka 411-8540, Japan. Tel.: +81 55 981 6754; Fax: +81 55 981 6762; E-mail:
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