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Mojumdar A, Granger C, Lunke M, Cobb JA. Loss of Dna2 fidelity results in decreased Exo1-mediated resection at DNA double-strand breaks. J Biol Chem 2024; 300:105708. [PMID: 38311177 PMCID: PMC10909748 DOI: 10.1016/j.jbc.2024.105708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 01/13/2024] [Accepted: 01/25/2024] [Indexed: 02/10/2024] Open
Abstract
A DNA double-strand break (DSB) is one of the most dangerous types of DNA damage that is repaired largely by homologous recombination or nonhomologous end-joining (NHEJ). The interplay of repair factors at the break directs which pathway is used, and a subset of these factors also function in more mutagenic alternative (alt) repair pathways. Resection is a key event in repair pathway choice and extensive resection, which is a hallmark of homologous recombination, and it is mediated by two nucleases, Exo1 and Dna2. We observed differences in resection and repair outcomes in cells harboring nuclease-dead dna2-1 compared with dna2Δ pif1-m2 that could be attributed to the level of Exo1 recovered at DSBs. Cells harboring dna2-1 showed reduced Exo1 localization, increased NHEJ, and a greater resection defect compared with cells where DNA2 was deleted. Both the resection defect and the increased rate of NHEJ in dna2-1 mutants were reversed upon deletion of KU70 or ectopic expression of Exo1. By contrast, when DNA2 was deleted, Exo1 and Ku70 recovery levels did not change; however, Nej1 increased as did the frequency of alt-end joining/microhomology-mediated end-joining repair. Our findings demonstrate that decreased Exo1 at DSBs contributed to the resection defect in cells expressing inactive Dna2 and highlight the complexity of understanding how functionally redundant factors are regulated in vivo to promote genome stability.
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Affiliation(s)
- Aditya Mojumdar
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Courtney Granger
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Martine Lunke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Jennifer A Cobb
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada.
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2
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Bai W, Huang M, Li C, Li J. The biological principles and advanced applications of DSB repair in CRISPR-mediated yeast genome editing. Synth Syst Biotechnol 2023; 8:584-596. [PMID: 37711546 PMCID: PMC10497738 DOI: 10.1016/j.synbio.2023.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 08/24/2023] [Accepted: 08/29/2023] [Indexed: 09/16/2023] Open
Abstract
To improve the performance of yeast cell factories for industrial production, extensive CRISPR-mediated genome editing systems have been applied by artificially creating double-strand breaks (DSBs) to introduce mutations with the assistance of intracellular DSB repair. Diverse strategies of DSB repair are required to meet various demands, including precise editing or random editing with customized gRNAs or a gRNA library. Although most yeasts remodeling techniques have shown rewarding performance in laboratory verification, industrial yeast strain manipulation relies only on very limited strategies. Here, we comprehensively reviewed the molecular mechanisms underlying recent industrial applications to provide new insights into DSB cleavage and repair pathways in both Saccharomyces cerevisiae and other unconventional yeast species. The discussion of DSB repair covers the most frequently used homologous recombination (HR) and nonhomologous end joining (NHEJ) strategies to the less well-studied illegitimate recombination (IR) pathways, such as single-strand annealing (SSA) and microhomology-mediated end joining (MMEJ). Various CRISPR-based genome editing tools and corresponding gene editing efficiencies are described. Finally, we summarize recently developed CRISPR-based strategies that use optimized DSB repair for genome-scale editing, providing a direction for further development of yeast genome editing.
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Affiliation(s)
- Wenxin Bai
- Institute of Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 100081, Beijing, PR China
- The BIT-QUB International Joint Laboratory in Synthetic Biology, Beijing, 100081, PR China
| | - Meilan Huang
- School of Chemistry and Chemical Engineering, David Keir Building, Queen's University Belfast, Stranmillis Road, Northern Ireland, BT9 5AG, Belfast, United Kingdom
- The BIT-QUB International Joint Laboratory in Synthetic Biology, Beijing, 100081, PR China
| | - Chun Li
- Institute of Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 100081, Beijing, PR China
- Key Lab for Industrial Biocatalysis, Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, PR China
| | - Jun Li
- Institute of Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 100081, Beijing, PR China
- The BIT-QUB International Joint Laboratory in Synthetic Biology, Beijing, 100081, PR China
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3
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Kan M, Huang T, Zhao P. Artificial chromosome technology and its potential application in plants. FRONTIERS IN PLANT SCIENCE 2022; 13:970943. [PMID: 36186059 PMCID: PMC9519882 DOI: 10.3389/fpls.2022.970943] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 08/26/2022] [Indexed: 06/16/2023]
Abstract
Plant genetic engineering and transgenic technology are powerful ways to study the function of genes and improve crop yield and quality in the past few years. However, only a few genes could be transformed by most available genetic engineering and transgenic technologies, so changes still need to be made to meet the demands for high throughput studies, such as investigating the whole genetic pathway of crop traits and avoiding undesirable genes simultaneously in the next generation. Plant artificial chromosome (PAC) technology provides a carrier which allows us to assemble multiple and specific genes to produce a variety of products by minichromosome. However, PAC technology also have limitations that may hinder its further development and application. In this review, we will introduce the current state of PACs technology from PACs formation, factors on PACs formation, problems and potential solutions of PACs and exogenous gene(s) integration.
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Affiliation(s)
- Manman Kan
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong, China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Tengbo Huang
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong, China
| | - Panpan Zhao
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong, China
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4
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Mojumdar A, Adam N, Cobb JA. Nej1 interacts with Sae2 at DNA double-stranded breaks to inhibit DNA resection. J Biol Chem 2022; 298:101937. [PMID: 35429499 PMCID: PMC9117546 DOI: 10.1016/j.jbc.2022.101937] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/03/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
The two major pathways of DNA double-strand break repair, nonhomologous end-joining and homologous recombination, are highly conserved from yeast to mammals. The regulation of 5′-DNA resection controls repair pathway choice and influences repair outcomes. Nej1 was first identified as a canonical NHEJ factor involved in stimulating the ligation of broken DNA ends, and more recently, it was shown to participate in DNA end-bridging and in the inhibition of 5′-resection mediated by the nuclease/helicase complex Dna2–Sgs1. Here, we show that Nej1 interacts with Sae2 to impact DSB repair in three ways. First, we show that Nej1 inhibits interaction of Sae2 with the Mre11–Rad50–Xrs2 complex and Sae2 localization to DSBs. Second, we found that Nej1 inhibits Sae2-dependent recruitment of Dna2 independently of Sgs1. Third, we determined that NEJ1 and SAE2 showed an epistatic relationship for end-bridging, an event that restrains broken DNA ends and reduces the frequency of genomic deletions from developing at the break site. Finally, we demonstrate that deletion of NEJ1 suppressed the synthetic lethality of sae2Δ sgs1Δ mutants, and that triple mutant viability was dependent on Dna2 nuclease activity. Taken together, these findings provide mechanistic insight to how Nej1 functionality inhibits the initiation of DNA resection, a role that is distinct from its involvement in end-joining repair at DSBs.
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Affiliation(s)
- Aditya Mojumdar
- Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine; University of Calgary; 3330 Hospital Drive N.W., Calgary, AB T2N 4N1, Canada
| | - Nancy Adam
- Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine; University of Calgary; 3330 Hospital Drive N.W., Calgary, AB T2N 4N1, Canada
| | - Jennifer A Cobb
- Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine; University of Calgary; 3330 Hospital Drive N.W., Calgary, AB T2N 4N1, Canada.
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5
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Mojumdar A, Adam N, Cobb J. Multifunctional properties of Nej1XLF C-terminus promote end-joining and impact DNA double-strand break repair pathway choice. DNA Repair (Amst) 2022; 115:103332. [DOI: 10.1016/j.dnarep.2022.103332] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/18/2022] [Accepted: 04/16/2022] [Indexed: 11/16/2022]
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6
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Bordelet H, Costa R, Brocas C, Dépagne J, Veaute X, Busso D, Batté A, Guérois R, Marcand S, Dubrana K. Sir3 heterochromatin protein promotes non-homologous end joining by direct inhibition of Sae2. EMBO J 2022; 41:e108813. [PMID: 34817085 PMCID: PMC8724767 DOI: 10.15252/embj.2021108813] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/02/2021] [Accepted: 11/04/2021] [Indexed: 01/07/2023] Open
Abstract
Heterochromatin is a conserved feature of eukaryotic chromosomes, with central roles in gene expression regulation and maintenance of genome stability. How heterochromatin proteins regulate DNA repair remains poorly described. In the yeast Saccharomyces cerevisiae, the silent information regulator (SIR) complex assembles heterochromatin-like chromatin at sub-telomeric chromosomal regions. SIR-mediated repressive chromatin limits DNA double-strand break (DSB) resection, thus protecting damaged chromosome ends during homologous recombination (HR). As resection initiation represents the crossroads between repair by non-homologous end joining (NHEJ) or HR, we asked whether SIR-mediated heterochromatin regulates NHEJ. We show that SIRs promote NHEJ through two pathways, one depending on repressive chromatin assembly, and the other relying on Sir3 in a manner that is independent of its heterochromatin-promoting function. Via physical interaction with the Sae2 protein, Sir3 impairs Sae2-dependent functions of the MRX (Mre11-Rad50-Xrs2) complex, thereby limiting Mre11-mediated resection, delaying MRX removal from DSB ends, and promoting NHEJ.
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Affiliation(s)
- Hélène Bordelet
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
- Régulation spatiale des génomes, Institut Pasteur, CNRS UMR3525ParisFrance
| | - Rafaël Costa
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Clémentine Brocas
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Jordane Dépagne
- CIGEx platform. Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Xavier Veaute
- CIGEx platform. Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Didier Busso
- CIGEx platform. Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Amandine Batté
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
- Center for Integrative GenomicsBâtiment GénopodeUniversity of LausanneLausanneSwitzerland
| | - Raphaël Guérois
- Institute for Integrative Biology of the Cell (I2BC)CEA, CNRS, Université Paris‐Sud, Université Paris‐SaclayGif‐sur‐YvetteFrance
| | - Stéphane Marcand
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Karine Dubrana
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
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7
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Roisné-Hamelin F, Pobiega S, Jézéquel K, Miron S, Dépagne J, Veaute X, Busso D, Du MHL, Callebaut I, Charbonnier JB, Cuniasse P, Zinn-Justin S, Marcand S. Mechanism of MRX inhibition by Rif2 at telomeres. Nat Commun 2021; 12:2763. [PMID: 33980827 PMCID: PMC8115599 DOI: 10.1038/s41467-021-23035-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 04/13/2021] [Indexed: 02/06/2023] Open
Abstract
Specific proteins present at telomeres ensure chromosome end stability, in large part through unknown mechanisms. In this work, we address how the Saccharomyces cerevisiae ORC-related Rif2 protein protects telomere. We show that the small N-terminal Rif2 BAT motif (Blocks Addition of Telomeres) previously known to limit telomere elongation and Tel1 activity is also sufficient to block NHEJ and 5' end resection. The BAT motif inhibits the ability of the Mre11-Rad50-Xrs2 complex (MRX) to capture DNA ends. It acts through a direct contact with Rad50 ATP-binding Head domains. Through genetic approaches guided by structural predictions, we identify residues at the surface of Rad50 that are essential for the interaction with Rif2 and its inhibition. Finally, a docking model predicts how BAT binding could specifically destabilise the DNA-bound state of the MRX complex. From these results, we propose that when an MRX complex approaches a telomere, the Rif2 BAT motif binds MRX Head in its ATP-bound resting state. This antagonises MRX transition to its DNA-bound state, and favours a rapid return to the ATP-bound state. Unable to stably capture the telomere end, the MRX complex cannot proceed with the subsequent steps of NHEJ, Tel1-activation and 5' resection.
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Affiliation(s)
- Florian Roisné-Hamelin
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Sabrina Pobiega
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Kévin Jézéquel
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Simona Miron
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Jordane Dépagne
- CIGEx, Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Xavier Veaute
- CIGEx, Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Didier Busso
- CIGEx, Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Marie-Hélène Le Du
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Isabelle Callebaut
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie de Physique des Matériaux et de Cosmochimie (IMPMC), Paris, France
| | - Jean-Baptiste Charbonnier
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Philippe Cuniasse
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Sophie Zinn-Justin
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Stéphane Marcand
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France.
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8
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Tripuraneni V, Memisoglu G, MacAlpine HK, Tran TQ, Zhu W, Hartemink AJ, Haber JE, MacAlpine DM. Local nucleosome dynamics and eviction following a double-strand break are reversible by NHEJ-mediated repair in the absence of DNA replication. Genome Res 2021; 31:775-788. [PMID: 33811083 PMCID: PMC8092003 DOI: 10.1101/gr.271155.120] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 03/26/2021] [Indexed: 12/27/2022]
Abstract
We interrogated at nucleotide resolution the spatiotemporal order of chromatin changes that occur immediately following a site-specific double-strand break (DSB) upstream of the PHO5 locus and its subsequent repair by nonhomologous end joining (NHEJ). We observed the immediate eviction of a nucleosome flanking the break and the repositioning of adjacent nucleosomes away from the break. These early chromatin events were independent of the end-processing Mre11-Rad50-Xrs2 (MRX) complex and preceded the MRX-dependent broad eviction of histones and DNA end-resectioning that extends up to ∼8 kb away from the break. We also examined the temporal dynamics of NHEJ-mediated repair in a G1-arrested population. Concomitant with DSB repair by NHEJ, we observed the redeposition and precise repositioning of nucleosomes at their originally occupied positions. This re-establishment of the prelesion chromatin landscape suggests that a DNA replication-independent mechanism exists to preserve epigenome organization following DSB repair.
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Affiliation(s)
- Vinay Tripuraneni
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Gonen Memisoglu
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA
| | - Heather K MacAlpine
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Trung Q Tran
- Department of Computer Science, Duke University, Durham, North Carolina 27708, USA
| | - Wei Zhu
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | | | - James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454, USA
| | - David M MacAlpine
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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9
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Hooshyar M, Jessulat M, Burnside D, Kluew A, Babu M, Golshani A. Deletion of yeast TPK1 reduces the efficiency of non-homologous end joining DNA repair. Biochem Biophys Res Commun 2020; 533:899-904. [DOI: 10.1016/j.bbrc.2020.09.083] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 09/20/2020] [Indexed: 12/12/2022]
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10
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Nej1 Interacts with Mre11 to Regulate Tethering and Dna2 Binding at DNA Double-Strand Breaks. Cell Rep 2020; 28:1564-1573.e3. [PMID: 31390569 PMCID: PMC6746346 DOI: 10.1016/j.celrep.2019.07.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 05/19/2019] [Accepted: 07/08/2019] [Indexed: 01/09/2023] Open
Abstract
Non-homologous end joining (NHEJ) and homologous recombination (HR) are the two major pathways of DNA double-strand break (DSB) repair and both are highly conserved from yeast to mammals. Nej1 has a role in DNA end-tethering at a DSB, and the Mre11/Rad50/Xrs2 (MRX) complex is important for its recruitment to the break. Nej1 and Dna2-Sgs1 interact with the C-terminal end of Mre11, which also includes the region where Rad50 binds. By characterizing the functionality of Nej1 in two rad50 mutants, which alter the structural features of MRX, we demonstrate that Nej1 inhibits the binding of Dna2 to Mre11 and Sgs1. Nej1 interactions with Mre11 promote tethering and inhibit hyper-resection, and when these events are compromised, large deletions develop at a DSB. The work indicates that Nej1 provides a layer of regulation to repair pathway choice and is consistent with its role in NHEJ. Mojumdar et al. characterize the role of Nej1 during double-strand break repair. They show Nej1 promotes non-homologous end joining (NHEJ) by tethering the broken DNA ends and by inhibiting hyper-resection mediated by Dna2-Sgs1.
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11
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Yu TY, Garcia VE, Symington LS. CDK and Mec1/Tel1-catalyzed phosphorylation of Sae2 regulate different responses to DNA damage. Nucleic Acids Res 2020; 47:11238-11249. [PMID: 31552432 PMCID: PMC6868371 DOI: 10.1093/nar/gkz814] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 09/09/2019] [Accepted: 09/20/2019] [Indexed: 11/14/2022] Open
Abstract
Sae2 functions in the DNA damage response by controlling Mre11-Rad50-Xrs2 (MRX)-catalyzed end resection, an essential step for homology-dependent repair of double-strand breaks (DSBs), and by attenuating DNA damage checkpoint signaling. Phosphorylation of Sae2 by cyclin-dependent kinase (CDK1/Cdc28) activates the Mre11 endonuclease, while the physiological role of Sae2 phosphorylation by Mec1 and Tel1 checkpoint kinases is not fully understood. Here, we compare the phenotype of sae2 mutants lacking the main CDK (sae2-S267A) or Mec1 and Tel1 phosphorylation sites (sae2-5A) with sae2Δ and Mre11 nuclease defective (mre11-nd) mutants. The phosphorylation-site mutations confer DNA damage sensitivity, but not to the same extent as sae2Δ. The sae2-S267A mutation is epistatic to mre11-nd for camptothecin (CPT) sensitivity and synergizes with sgs1Δ, whereas sae2-5A synergizes with mre11-nd and exhibits epistasis with sgs1Δ. We find that attenuation of checkpoint signaling by Sae2 is mostly independent of Mre11 endonuclease activation but requires Mec1 and Tel1-dependent phosphorylation of Sae2. These results support a model whereby CDK-catalyzed phosphorylation of Sae2 activates resection via Mre11 endonuclease, whereas Sae2 phosphorylation by Mec1 and Tel1 promotes resection by the Dna2-Sgs1 and Exo1 pathways indirectly by dampening the DNA damage response.
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Affiliation(s)
- Tai-Yuan Yu
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Valerie E Garcia
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.,Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY 10032, USA
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12
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Alabdullah AK, Borrill P, Martin AC, Ramirez-Gonzalez RH, Hassani-Pak K, Uauy C, Shaw P, Moore G. A Co-Expression Network in Hexaploid Wheat Reveals Mostly Balanced Expression and Lack of Significant Gene Loss of Homeologous Meiotic Genes Upon Polyploidization. FRONTIERS IN PLANT SCIENCE 2019; 10:1325. [PMID: 31681395 PMCID: PMC6813927 DOI: 10.3389/fpls.2019.01325] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 09/24/2019] [Indexed: 05/05/2023]
Abstract
Polyploidization has played an important role in plant evolution. However, upon polyploidization, the process of meiosis must adapt to ensure the proper segregation of increased numbers of chromosomes to produce balanced gametes. It has been suggested that meiotic gene (MG) duplicates return to a single copy following whole genome duplication to stabilize the polyploid genome. Therefore, upon the polyploidization of wheat, a hexaploid species with three related (homeologous) genomes, the stabilization process may have involved rapid changes in content and expression of MGs on homeologous chromosomes (homeologs). To examine this hypothesis, sets of candidate MGs were identified in wheat using co-expression network analysis and orthology informed approaches. In total, 130 RNA-Seq samples from a range of tissues including wheat meiotic anthers were used to define co-expressed modules of genes. Three modules were significantly correlated with meiotic tissue samples but not with other tissue types. These modules were enriched for GO terms related to cell cycle, DNA replication, and chromatin modification and contained orthologs of known MGs. Overall, 74.4% of genes within these meiosis-related modules had three homeologous copies which was similar to other tissue-related modules. Amongst wheat MGs identified by orthology, rather than co-expression, the majority (93.7%) were either retained in hexaploid wheat at the same number of copies (78.4%) or increased in copy number (15.3%) compared to ancestral wheat species. Furthermore, genes within meiosis-related modules showed more balanced expression levels between homeologs than genes in non-meiosis-related modules. Taken together, our results do not support extensive gene loss nor changes in homeolog expression of MGs upon wheat polyploidization. The construction of the MG co-expression network allowed identification of hub genes and provided key targets for future studies.
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Affiliation(s)
| | - Philippa Borrill
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | | | | | - Keywan Hassani-Pak
- Computational and Analytical Sciences, Rothamsted Research, Harpenden, United Kingdom
| | - Cristobal Uauy
- John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Peter Shaw
- John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Graham Moore
- John Innes Centre, Norwich Research Park, Norwich, United Kingdom
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13
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Liu Z, Yu M, Fei B, Sun J, Wang D. Nonhomologous end joining key factor XLF enhances both 5-florouracil and oxaliplatin resistance in colorectal cancer. Onco Targets Ther 2019; 12:2095-2104. [PMID: 30936724 PMCID: PMC6430989 DOI: 10.2147/ott.s192923] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Background Colorectal cancer (CRC) is the third commonly diagnosed cancer with a high risk of death. After curative surgery, 40% of patients will have metastases or develop recurrence. Therefore, chemotherapy is significantly responsible as the major therapy method. However, chemoresistance is found in almost all metastatic patients and remains a critical obstacle to curing CRC. Materials and methods Cell viability is analyzed by sulforhodamine B staining assay. The nonhomologous end joining (NHEJ) repair ability of each cell line was determined by NHEJ reporter assay. mRNA expression levels of NHEJ factors are detected by real-time quantitative polymerase chain reaction. The protein expression levels were observed by western blot assay. Results Our study found that 5-florouracil (5-Fu) and oxaliplatin (OXA)-resistant HCT116 and LS174T cells showed upregulated efficiency of DNA double-strand repair pathway NHEJ. We then identified that the NHEJ key factor XLF is responsible for the chemoresistance and XLF deficiency sensitizes CRC cells to 5-Fu and OXA significantly. Conclusion Our research first demonstrates that the NHEJ pathway, especially its key factor XLF, significantly contributes to chemoresistance in CRC.
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Affiliation(s)
- Zhuo Liu
- Department of Gastrointestinal Colorectal and Anal Surgery, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130021, China
| | - Miao Yu
- Department of Gastrointestinal Colorectal and Anal Surgery, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130021, China
| | - Bingyuan Fei
- Department of Gastrointestinal Colorectal and Anal Surgery, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130021, China
| | - Jing Sun
- Department of Biochemistry and Molecular Medicine, The George Washington University, Washington, DC 20052, USA
| | - Dongxin Wang
- Department of Anesthesiology, Jilin Cancer Hospital, Changchun, Jilin 130021, China,
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14
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Oh J, Symington LS. Role of the Mre11 Complex in Preserving Genome Integrity. Genes (Basel) 2018; 9:E589. [PMID: 30501098 PMCID: PMC6315862 DOI: 10.3390/genes9120589] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 12/12/2022] Open
Abstract
DNA double-strand breaks (DSBs) are hazardous lesions that threaten genome integrity and cell survival. The DNA damage response (DDR) safeguards the genome by sensing DSBs, halting cell cycle progression and promoting repair through either non-homologous end joining (NHEJ) or homologous recombination (HR). The Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex is central to the DDR through its structural, enzymatic, and signaling roles. The complex tethers DNA ends, activates the Tel1/ATM kinase, resolves protein-bound or hairpin-capped DNA ends, and maintains telomere homeostasis. In addition to its role at DSBs, MRX/N associates with unperturbed replication forks, as well as stalled replication forks, to ensure complete DNA synthesis and to prevent chromosome rearrangements. Here, we summarize the significant progress made in characterizing the MRX/N complex and its various activities in chromosome metabolism.
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Affiliation(s)
- Julyun Oh
- Biological Sciences Program, Columbia University, New York, NY 10027, USA.
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
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15
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Oh J, Lee SJ, Rothstein R, Symington LS. Xrs2 and Tel1 Independently Contribute to MR-Mediated DNA Tethering and Replisome Stability. Cell Rep 2018; 25:1681-1692.e4. [PMID: 30428339 PMCID: PMC6317890 DOI: 10.1016/j.celrep.2018.10.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 09/08/2018] [Accepted: 10/05/2018] [Indexed: 02/04/2023] Open
Abstract
The yeast Mre11-Rad50-Xrs2 (MRX) complex has structural, signaling, and catalytic functions in the response to DNA damage. Xrs2, the eukaryotic-specific component of the complex, is required for nuclear import of Mre11 and Rad50 and to recruit the Tel1 kinase to damage sites. We show that nuclear-localized MR complex (Mre11-NLS) catalyzes homology-dependent repair without Xrs2, but MR cannot activate Tel1, and it fails to tether DSBs, resulting in sensitivity to genotoxins, replisome instability, and increased gross chromosome rearrangements (GCRs). Fusing the Tel1 interaction domain from Xrs2 to Mre11-NLS is sufficient to restore telomere elongation and Tel1 signaling to Xrs2-deficient cells. Furthermore, Tel1 stabilizes Mre11-DNA association, and this stabilization function becomes important for DNA damage resistance in the absence of Xrs2. Enforcing Tel1 recruitment to the nuclear MR complex fully rescues end tethering and stalled replication fork stability, and suppresses GCRs, highlighting important roles for Xrs2 and Tel1 to ensure optimal MR activity.
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Affiliation(s)
- Julyun Oh
- Biological Sciences Program, Columbia University, New York, NY 10027, USA; Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - So Jung Lee
- Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Rodney Rothstein
- Biological Sciences Program, Columbia University, New York, NY 10027, USA; Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Lorraine S Symington
- Biological Sciences Program, Columbia University, New York, NY 10027, USA; Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA; Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY 10032, USA.
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16
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Matsuzaki K, Shinohara M. Casein kinase II phosphorylates the C-terminal region of Lif1 to promote the Lif1-Xrs2 interaction needed for non-homologous end joining. Biochem Biophys Res Commun 2018; 501:1080-1084. [PMID: 29778533 DOI: 10.1016/j.bbrc.2018.05.111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 05/15/2018] [Indexed: 12/25/2022]
Abstract
A DNA double strand break (DSB) is one of the most cytotoxic DNA lesions, but it can be repaired by non-homologous end joining (NHEJ) or by homologous recombination. The choice between these two repair pathways depends on the cell cycle stage. Although NHEJ constitutes a simple re-ligation reaction, the regulatory mechanism(s) controlling its activity has not been fully characterized. Lif1 is a regulatory subunit of the NHEJ-specific DNA ligase IV and interacts with Xrs2 of the MRX complex which is a key factor in DSB repair. Specifically, the C-terminal region of Lif1, which contains a CK2-specific phosphorylation motif, interacts with the FHA domain of Xrs2 during canonical- NHEJ (C-NHEJ). Herein, we show that Lif1 and Cka2, a catalytic subunit of yeast CK2, interact and that the C-terminal phosphorylation consensus motif in Lif1 is phosphorylated by recombinant CK2. These observations suggest that phosphorylation of Lif1 by CK2 at a DSB site promotes the Lif1-Xrs2 interaction and facilitates C-NHEJ.
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Affiliation(s)
- Kenichiro Matsuzaki
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Miki Shinohara
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan; Department of Advanced Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara, 631-8505, Japan.
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17
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Ku DNA End-Binding Activity Promotes Repair Fidelity and Influences End-Processing During Nonhomologous End-Joining in Saccharomyces cerevisiae. Genetics 2018; 209:115-128. [PMID: 29500182 DOI: 10.1534/genetics.117.300672] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 02/25/2018] [Indexed: 12/21/2022] Open
Abstract
The Ku heterodimer acts centrally in nonhomologous end-joining (NHEJ) of DNA double-strand breaks (DSB). Saccharomyces cerevisiae Ku, like mammalian Ku, binds and recruits NHEJ factors to DSB ends. Consequently, NHEJ is virtually absent in yeast Ku null (yku70∆ or yku80∆) strains. Previously, we unexpectedly observed imprecise NHEJ proficiency in a yeast Ku mutant with impaired DNA end-binding (DEB). However, how DEB impairment supported imprecise NHEJ was unknown. Here, we found imprecise NHEJ proficiency to be a feature of a panel of DEB-impaired Ku mutants and that DEB impairment resulted in a deficiency in precise NHEJ. These results suggest that DEB-impaired Ku specifically promotes error-prone NHEJ. Epistasis analysis showed that classical NHEJ factors, as well as novel and previously characterized NHEJ-specific residues of Ku, are required for the distinct error-prone repair in a Ku DEB mutant. However, sequencing of repair junctions revealed that imprecise repair in Ku DEB mutants was almost exclusively characterized by small deletions, in contrast to the majority of insertions that define imprecise repair in wild-type strains. Notably, while sequencing indicated a lack of Pol4-dependent insertions at the site of repair, Pol2 exonuclease activity, which mediates small deletions in NHEJ, contributed to imprecise NHEJ in a Ku DEB mutant. The deletions were smaller than in Ku-independent microhomology-mediated end-joining (MMEJ) and were neither promoted by Mre11 nuclease activity nor Sae2 Thus, the quality of Ku's engagement at the DNA end influences end-processing during NHEJ and DEB impairment unmasks a Ku-dependent error-prone pathway of end-joining distinct from MMEJ.
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18
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Wang W, Daley JM, Kwon Y, Krasner DS, Sung P. Plasticity of the Mre11-Rad50-Xrs2-Sae2 nuclease ensemble in the processing of DNA-bound obstacles. Genes Dev 2018; 31:2331-2336. [PMID: 29321177 PMCID: PMC5795780 DOI: 10.1101/gad.307900.117] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/07/2017] [Indexed: 11/25/2022]
Abstract
Wang et al. show that the Ku complex shields DNA ends from exonucleolytic digestion but facilitates endonucleolytic scission by MRX with a dependence on ATP and Sae2. The budding yeast Mre11–Rad50–Xrs2 (MRX) complex and Sae2 function together in DNA end resection during homologous recombination. Here we show that the Ku complex shields DNA ends from exonucleolytic digestion but facilitates endonucleolytic scission by MRX with a dependence on ATP and Sae2. The incision site is enlarged into a DNA gap via the exonuclease activity of MRX, which is stimulated by Sae2 without ATP being present. RPA renders a partially resected or palindromic DNA structure susceptible to MRX–Sae2, and internal protein blocks also trigger DNA cleavage. We present models for how MRX–Sae2 creates entry sites for the long-range resection machinery.
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Affiliation(s)
- Weibin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - James M Daley
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Youngho Kwon
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Danielle S Krasner
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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19
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Sorenson KS, Mahaney BL, Lees-Miller SP, Cobb JA. The non-homologous end-joining factor Nej1 inhibits resection mediated by Dna2-Sgs1 nuclease-helicase at DNA double strand breaks. J Biol Chem 2017; 292:14576-14586. [PMID: 28679532 DOI: 10.1074/jbc.m117.796011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 07/03/2017] [Indexed: 12/25/2022] Open
Abstract
Double strand breaks (DSBs) represent highly deleterious DNA damage and need to be accurately repaired. Homology-directed repair and non-homologous end joining (NHEJ) are the two major DSB repair pathways that are highly conserved from yeast to mammals. The choice between these pathways is largely based on 5' to 3' DNA resection, and NHEJ proceeds only if resection has not been initiated. In yeast, yKu70/80 rapidly localizes to the break, protecting DNA ends from nuclease accessibility, and recruits additional NHEJ factors, including Nej1 and Lif1. Cells harboring the nej1-V338A mutant exhibit NHEJ-mediated repair deficiencies and hyper-resection 0.15 kb from the DSB that was dependent on the nuclease activity of Dna2-Sgs1. The integrity of Nej1 is also important for inhibiting long-range resection, 4.8 kb from the break, and for preventing the formation of large genomic deletions at sizes >700 bp around the break. Nej1V338A localized to a DSB similarly to WT Nej1, indicating that the Nej1-Lif1 interaction becomes critical for blocking hyper-resection mainly after their recruitment to the DSB. This work highlights that Nej1 inhibits 5' DNA hyper-resection mediated by Dna2-Sgs1, a function distinct from its previously reported role in supporting Dnl4 ligase activity, and has implications for repair pathway choice and resection regulation upon DSB formation.
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Affiliation(s)
- Kyle S Sorenson
- From the Departments of Biochemistry and Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive N. W., Calgary, Alberta T2N 4N1, Canada
| | - Brandi L Mahaney
- From the Departments of Biochemistry and Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive N. W., Calgary, Alberta T2N 4N1, Canada
| | - Susan P Lees-Miller
- From the Departments of Biochemistry and Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive N. W., Calgary, Alberta T2N 4N1, Canada
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20
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Regulation of non-homologous end joining via post-translational modifications of components of the ligation step. Curr Genet 2016; 63:591-605. [PMID: 27915381 DOI: 10.1007/s00294-016-0670-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/25/2016] [Accepted: 11/26/2016] [Indexed: 12/29/2022]
Abstract
DNA double-strand breaks are the most serious type of DNA damage and non-homologous end joining (NHEJ) is an important pathway for their repair. In Saccharomyces cerevisiae, three complexes mediate the canonical NHEJ pathway, Ku (Ku70/Ku80), MRX (Mre11/Rad50/Xrs2) and DNA ligase IV (Dnl4/Lif1). Mammalian NHEJ is more complex, primarily as a consequence of the fact that more factors are involved in the process, and also because higher chromatin organization and more complex regulatory networks exist in mammals. In addition, a stronger interconnection between the NHEJ and DNA damage response (DDR) pathways seems to occur in mammals compared to yeast. DDR employs multiple post-translational modifications (PTMs) of the target proteins and mutual crosstalk among them to ensure highly efficient down-stream effects. Checkpoint-mediated phosphorylation is the best understood PTM that regulates DDR, although recently SUMOylation has also been shown to be involved. Both phosphorylation and SUMOylation affect components of NHEJ. In this review, we discuss a role of these two PTMs in regulation of NHEJ via targeting the components of the ligation step.
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21
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Xrs2 Dependent and Independent Functions of the Mre11-Rad50 Complex. Mol Cell 2016; 64:405-415. [PMID: 27746018 DOI: 10.1016/j.molcel.2016.09.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/22/2016] [Accepted: 09/08/2016] [Indexed: 02/04/2023]
Abstract
The Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex orchestrates the cellular response to DSBs through its structural, enzymatic, and signaling roles. Xrs2/Nbs1 is essential for nuclear translocation of Mre11, but its role as a component of the complex is not well defined. Here, we demonstrate that nuclear localization of Mre11 (Mre11-NLS) is able to bypass several functions of Xrs2, including DNA end resection, meiosis, hairpin resolution, and cellular resistance to clastogens. Using purified components, we show that the MR complex has equivalent activity to MRX in cleavage of protein-blocked DNA ends. Although Xrs2 physically interacts with Sae2, we found that end resection in its absence remains Sae2 dependent in vivo and in vitro. MRE11-NLS was unable to rescue the xrs2Δ defects in Tel1/ATM kinase signaling and non-homologous end joining, consistent with the role of Xrs2 as a chaperone and adaptor protein coordinating interactions between the MR complex and other repair proteins.
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22
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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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23
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Emerson CH, Bertuch AA. Consider the workhorse: Nonhomologous end-joining in budding yeast. Biochem Cell Biol 2016; 94:396-406. [PMID: 27240172 DOI: 10.1139/bcb-2016-0001] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
DNA double strand breaks (DSBs) are dangerous sources of genome instability and must be repaired by the cell. Nonhomologous end-joining (NHEJ) is an evolutionarily conserved pathway to repair DSBs by direct ligation of the ends, with no requirement for a homologous template. While NHEJ is the primary DSB repair pathway in mammalian cells, conservation of the core NHEJ factors throughout eukaryotes makes the pathway attractive for study in model organisms. The budding yeast, Saccharomyces cerevisiae, has been used extensively to develop a functional picture of NHEJ. In this review, we will discuss the current understanding of NHEJ in S. cerevisiae. Topics include canonical end-joining, alternative end-joining, and pathway regulation. Particular attention will be paid to the NHEJ mechanism involving core factors, including Yku70/80, Dnl4, Lif1, and Nej1, as well as the various factors implicated in the processing of the broken ends. The relevance of chromatin dynamics to NHEJ will also be discussed. This review illustrates the use of S. cerevisiae as a powerful system to understand the principles of NHEJ, as well as in pioneering the direction of the field.
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Affiliation(s)
- Charlene H Emerson
- a Graduate Program in Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,b Departments of Pediatrics and Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Alison A Bertuch
- b Departments of Pediatrics and Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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24
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Liang Z, Sunder S, Nallasivam S, Wilson TE. Overhang polarity of chromosomal double-strand breaks impacts kinetics and fidelity of yeast non-homologous end joining. Nucleic Acids Res 2016; 44:2769-81. [PMID: 26773053 PMCID: PMC4824102 DOI: 10.1093/nar/gkw013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/05/2016] [Indexed: 12/21/2022] Open
Abstract
Non-homologous end joining (NHEJ) is the main repair pathway for DNA double-strand breaks (DSBs) in cells with limited 5′ resection. To better understand how overhang polarity of chromosomal DSBs affects NHEJ, we made site-specific 5′-overhanging DSBs (5′ DSBs) in yeast using an optimized zinc finger nuclease at an efficiency that approached HO-induced 3′ DSB formation. When controlled for the extent of DSB formation, repair monitoring suggested that chromosomal 5′ DSBs were rejoined more efficiently than 3′ DSBs, consistent with a robust recruitment of NHEJ proteins to 5′ DSBs. Ligation-mediated qPCR revealed that Mre11-Rad50-Xrs2 rapidly modified 5′ DSBs and facilitated protection of 3′ DSBs, likely through recognition of overhang polarity by the Mre11 nuclease. Next-generation sequencing revealed that NHEJ at 5′ DSBs had a higher mutation frequency, and validated the differential requirement of Pol4 polymerase at 3′ and 5′ DSBs. The end processing enzyme Tdp1 did not impact joining fidelity at chromosomal 5′ DSBs as in previous plasmid studies, although Tdp1 was recruited to only 5′ DSBs in a Ku-independent manner. These results suggest distinct DSB handling based on overhang polarity that impacts NHEJ kinetics and fidelity through differential recruitment and action of DSB modifying enzymes.
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Affiliation(s)
- Zhuobin Liang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sham Sunder
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Thomas E Wilson
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
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Yeast DNA ligase IV mutations reveal a nonhomologous end joining function of BRCT1 distinct from XRCC4/Lif1 binding. DNA Repair (Amst) 2015; 24:37-45. [PMID: 25457772 DOI: 10.1016/j.dnarep.2014.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Revised: 08/23/2014] [Accepted: 10/02/2014] [Indexed: 02/03/2023]
Abstract
LIG4/Dnl4 is the DNA ligase that (re)joins DNA double-strand breaks (DSBs) via nonhomologous end joining (NHEJ), an activity supported by binding of its tandem BRCT domains to the ligase accessory protein XRCC4/Lif1. We screened a panel of 88 distinct ligase mutants to explore the structure–function relationships of the yeast Dnl4 BRCT domains and inter-BRCT linker in NHEJ. Screen results suggested two distinct classes of BRCT mutations with differential effects on Lif1 interaction as compared to NHEJ completion. Validated constructs confirmed that D800K and GG(868:869)AA mutations, which target the Lif1 binding interface, showed a severely defective Dnl4–Lif1 interaction but a less consistent and often small decrease in NHEJ activity in some assays, as well as nearly normal levels of Dnl4 accumulation at DSBs. In contrast, mutants K742A and KTT(742:744)ATA, which target the β3-α2 region of the first BRCT domain, substantially decreased NHEJ function commensurate with a large defect in Dnl4 recruitment to DSBs, despite a comparatively greater preservation of the Lif1 interaction. Together, these separation-of-function mutants indicate that Dnl4 BRCT1 supports DSB recruitment and NHEJ in a manner distinct from Lif1 binding and reveal a complexity of Dnl4 BRCT domain functions in support of stable DSB association.
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26
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Spindle Checkpoint Factors Bub1 and Bub2 Promote DNA Double-Strand Break Repair by Nonhomologous End Joining. Mol Cell Biol 2015; 35:2448-63. [PMID: 25963654 DOI: 10.1128/mcb.00007-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 04/29/2015] [Indexed: 12/24/2022] Open
Abstract
The nonhomologous end-joining (NHEJ) pathway is essential for the preservation of genome integrity, as it efficiently repairs DNA double-strand breaks (DSBs). Previous biochemical and genetic investigations have indicated that, despite the importance of this pathway, the entire complement of genes regulating NHEJ remains unknown. To address this, we employed a plasmid-based NHEJ DNA repair screen in budding yeast (Saccharomyces cerevisiae) using 369 putative nonessential DNA repair-related components as queries. Among the newly identified genes associated with NHEJ deficiency upon disruption are two spindle assembly checkpoint kinases, Bub1 and Bub2. Both observation of resulting phenotypes and chromatin immunoprecipitation demonstrated that Bub1 and -2, either alone or in combination with cell cycle regulators, are recruited near the DSB, where phosphorylated Rad53 or H2A accumulates. Large-scale proteomic analysis of Bub kinases phosphorylated in response to DNA damage identified previously unknown kinase substrates on Tel1 S/T-Q sites. Moreover, Bub1 NHEJ function appears to be conserved in mammalian cells. 53BP1, which influences DSB repair by NHEJ, colocalizes with human BUB1 and is recruited to the break sites. Thus, while Bub is not a core component of NHEJ machinery, our data support its dual role in mitotic exit and promotion of NHEJ repair in yeast and mammals.
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27
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Role of the yeast DNA repair protein Nej1 in end processing during the repair of DNA double strand breaks by non-homologous end joining. DNA Repair (Amst) 2015; 31:1-10. [PMID: 25942368 DOI: 10.1016/j.dnarep.2015.04.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/06/2015] [Accepted: 04/13/2015] [Indexed: 11/22/2022]
Abstract
DNA double strand breaks (DSB)s often require end processing prior to joining during their repair by non-homologous end joining (NHEJ). Although the yeast proteins, Pol4, a Pol X family DNA polymerase, and Rad27, a nuclease, participate in the end processing reactions of NHEJ, the mechanisms underlying the recruitment of these factors to DSBs are not known. Here we demonstrate that Nej1, a NHEJ factor that interacts with and modulates the activity of the NHEJ DNA ligase complex (Dnl4/Lif1), physically and functionally interacts with both Pol4 and Rad27. Notably, Nej1 and Dnl4/Lif1, which also interacts with both Pol4 and Rad27, independently recruit the end processing factors to in vivo DSBs via mechanisms that are additive rather than redundant. As was observed with Dnl4/Lif1, the activities of both Pol4 and Rad27 were enhanced by the interaction with Nej1. Furthermore, Nej1 increased the joining of incompatible DNA ends in reconstituted reactions containing Pol4, Rad27 and Dnl4/Lif1, indicating that the stimulatory activities of Nej1 and Dnl4/Lif1 are also additive. Together our results reveal novel roles for Nej1 in the recruitment of Pol4 and Rad27 to in vivo DSBs and the coordination of the end processing and ligation reactions of NHEJ.
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28
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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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Marcand S. How do telomeres and NHEJ coexist? Mol Cell Oncol 2014; 1:e963438. [PMID: 27308342 PMCID: PMC4904885 DOI: 10.4161/23723548.2014.963438] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 08/01/2014] [Accepted: 08/07/2014] [Indexed: 12/21/2022]
Abstract
The telomeres of eukaryotes are stable open double-strand ends that coexist with nonhomologous end joining (NHEJ), the repair pathway that directly ligates DNA ends generated by double-strand breaks. Since a single end-joining event between 2 telomeres generates a circular chromosome or an unstable dicentric chromosome, NHEJ must be prevented from acting on telomeres. Multiple mechanisms mediated by telomere factors act in synergy to achieve this inhibition.
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Affiliation(s)
- Stéphane Marcand
- CEA; DSV/IRCM/SIGRR/LTR; Fontenay-aux-roses; France; INSERM UMR 967; Fontenay-aux-roses; France
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Genome-wide screens for sensitivity to ionizing radiation identify the fission yeast nonhomologous end joining factor Xrc4. G3-GENES GENOMES GENETICS 2014; 4:1297-306. [PMID: 24847916 PMCID: PMC4455778 DOI: 10.1534/g3.114.011841] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nonhomologous end joining (NHEJ) is the main means for repairing DNA double-strand breaks (DSBs) in human cells. Molecular understanding of NHEJ has benefited from analyses in the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe. In human cells, the DNA ligation reaction of the classical NHEJ pathway is carried out by a protein complex composed of DNA ligase IV (LigIV) and XRCC4. In S. cerevisiae, this reaction is catalyzed by a homologous complex composed of Dnl4 and Lif1. Intriguingly, no homolog of XRCC4 has been found in S. pombe, raising the possibility that such a factor may not always be required for classical NHEJ. Here, through screening the ionizing radiation (IR) sensitivity phenotype of a genome-wide fission yeast deletion collection in both the vegetative growth state and the spore state, we identify Xrc4, a highly divergent homolog of human XRCC4. Like other fission yeast NHEJ factors, Xrc4 is critically important for IR resistance of spores, in which no homologous recombination templates are available. Using both extrachromosomal and chromosomal DSB repair assays, we show that Xrc4 is essential for classical NHEJ. Exogenously expressed Xrc4 colocalizes with the LigIV homolog Lig4 at the chromatin region of the nucleus in a mutually dependent manner. Furthermore, like their human counterparts, Xrc4 and Lig4 interact with each other and this interaction requires the inter-BRCT linker and the second BRCT domain of Lig4. Our discovery of Xrc4 suggests that an XRCC4 family protein is universally required for classical NHEJ in eukaryotes.
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31
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Lin JS, Wu HH, Hsu PH, Ma LS, Pang YY, Tsai MD, Lai EM. Fha interaction with phosphothreonine of TssL activates type VI secretion in Agrobacterium tumefaciens. PLoS Pathog 2014; 10:e1003991. [PMID: 24626341 PMCID: PMC3953482 DOI: 10.1371/journal.ppat.1003991] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 01/27/2014] [Indexed: 11/26/2022] Open
Abstract
The type VI secretion system (T6SS) is a widespread protein secretion system found in many Gram-negative bacteria. T6SSs are highly regulated by various regulatory systems at multiple levels, including post-translational regulation via threonine (Thr) phosphorylation. The Ser/Thr protein kinase PpkA is responsible for this Thr phosphorylation regulation, and the forkhead-associated (FHA) domain-containing Fha-family protein is the sole T6SS phosphorylation substrate identified to date. Here we discovered that TssL, the T6SS inner-membrane core component, is phosphorylated and the phosphorylated TssL (p-TssL) activates type VI subassembly and secretion in a plant pathogenic bacterium, Agrobacterium tumefaciens. Combining genetic and biochemical approaches, we demonstrate that TssL is phosphorylated at Thr 14 in a PpkA-dependent manner. Further analysis revealed that the PpkA kinase activity is responsible for the Thr 14 phosphorylation, which is critical for the secretion of the T6SS hallmark protein Hcp and the putative toxin effector Atu4347. TssL phosphorylation is not required for the formation of the TssM-TssL inner-membrane complex but is critical for TssM conformational change and binding to Hcp and Atu4347. Importantly, Fha specifically interacts with phosphothreonine of TssL via its pThr-binding motif in vivo and in vitro and this interaction is crucial for TssL interaction with Hcp and Atu4347 and activation of type VI secretion. In contrast, pThr-binding ability of Fha is dispensable for TssM structural transition. In conclusion, we discover a novel Thr phosphorylation event, in which PpkA phosphorylates TssL to activate type VI secretion via its direct binding to Fha in A. tumefaciens. A model depicting an ordered TssL phosphorylation-induced T6SS assembly pathway is proposed. The bacterial type VI secretion system (T6SS) resembles a contractile phage tail structure and functions to deliver effectors to eukaryotic or prokaryotic target cells for the survival of many pathogenic bacteria. T6SS is highly regulated by various regulatory systems at multiple levels in response to environmental cues. Post-translational regulation via threonine (Thr) phosphorylation is an emerging theme in regulating prokaryotic signaling, including T6SS; the knowledge is mainly contributed by studies of Hcp secretion island 1-encoded T6SS (H1-T6SS) of Pseudomonas aeruginosa. Here, we discover a new phosphorylated target, a T6SS core-component TssL, and demonstrate that this Thr phosphorylation event post-translationally regulates type VI secretion in a plant pathogenic bacterium, Agrobacterium tumefaciens. We provide the first demonstration that the specific binding of Fha, a forkhead-associated domain-containing protein, to the phosphorylated target is required to stimulate type VI secretion. Genetic and biochemical data strongly suggest an ordered TssL-phosphorylation–dependent assembly and secretion pathway.
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Affiliation(s)
- Jer-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Hsin-Hui Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Structural Biology Program, National Tsing Hua University, Hsinchu, Taiwan; Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan
| | - Pang-Hung Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Genomics Research Center, Academia Sinica, Taipei, Taiwan; Department of Life Science, Institute of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Taiwan
| | - Lay-Sun Ma
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Yin-Yuin Pang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Ming-Daw Tsai
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Structural Biology Program, National Tsing Hua University, Hsinchu, Taiwan; Genomics Research Center, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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Non-homologous end joining often uses microhomology: implications for alternative end joining. DNA Repair (Amst) 2014; 17:74-80. [PMID: 24613510 DOI: 10.1016/j.dnarep.2014.02.006] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/27/2014] [Accepted: 02/10/2014] [Indexed: 11/20/2022]
Abstract
Artemis and PALF (also called APLF) appear to be among the primary nucleases involved in non-homologous end joining (NHEJ) and responsible for most nucleolytic end processing in NHEJ. About 60% of NHEJ events show an alignment of the DNA ends that use 1 or 2bp of microhomology (MH) between the two DNA termini. Thus, MH is a common feature of NHEJ. For most naturally occurring human chromosomal deletions (e.g., after oxidative damage or radiation) and translocations, such as those seen in human neoplasms and as well as inherited chromosomal structural variations, MH usage occurs at a frequency that is typical of NHEJ, and does not suggest major involvement of alternative pathways that require more extensive MH. Though we mainly focus on human NHEJ at double-strand breaks, comparison on these points to other eukaryotes, primarily S. cerevisiae, is informative.
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Mahaney BL, Lees-Miller SP, Cobb JA. The C-terminus of Nej1 is critical for nuclear localization and non-homologous end-joining. DNA Repair (Amst) 2013; 14:9-16. [PMID: 24369855 DOI: 10.1016/j.dnarep.2013.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 11/14/2013] [Accepted: 12/03/2013] [Indexed: 11/25/2022]
Abstract
Nej1 is an essential factor in the non-homologous end-joining (NHEJ) pathway and interacts with the DNA ligase complex, Lif1-Dnl4, through interactions with Lif1. We have mapped K331-V338 in the C-terminal region of Nej1 to be critical for its functionality during repair. Truncation and alanine scanning mutagenesis have been used to identify a motif in Nej1, KKRK (331-334), which is important for both nuclear targeting and NHEJ repair after localization. We have identified F335-V338 to be important for proper interaction with Lif1, however this region is not required for Nej1 recruitment to HO endonuclease-induced DNA double-strand breaks in vivo. Phenylalanine at position 335 is particularly important for the role of Nej1 in repair and the loss of association between Nej1 and Lif1 correlates with a decrease in cell survival upon either transient or continuous HO expression in nej1 mutants.
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Affiliation(s)
- Brandi L Mahaney
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada T2N 4N1
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada T2N 4N1
| | - Jennifer A Cobb
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada T2N 4N1.
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34
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Interplays between ATM/Tel1 and ATR/Mec1 in sensing and signaling DNA double-strand breaks. DNA Repair (Amst) 2013; 12:791-9. [PMID: 23953933 DOI: 10.1016/j.dnarep.2013.07.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 07/23/2013] [Indexed: 01/13/2023]
Abstract
DNA double-strand breaks (DSBs) are highly hazardous for genome integrity because they have the potential to cause mutations, chromosomal rearrangements and genomic instability. The cellular response to DSBs is orchestrated by signal transduction pathways, known as DNA damage checkpoints, which are conserved from yeasts to humans. These pathways can sense DNA damage and transduce this information to specific cellular targets, which in turn regulate cell cycle transitions and DNA repair. The mammalian protein kinases ATM and ATR, as well as their budding yeast corresponding orthologs Tel1 and Mec1, act as master regulators of the checkpoint response to DSBs. Here, we review the early steps of DSB processing and the role of DNA-end structures in activating ATM/Tel1 and ATR/Mec1 in an orderly and reciprocal manner.
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35
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Chiruvella KK, Liang Z, Birkeland SR, Basrur V, Wilson TE. Saccharomyces cerevisiae DNA ligase IV supports imprecise end joining independently of its catalytic activity. PLoS Genet 2013; 9:e1003599. [PMID: 23825968 PMCID: PMC3694833 DOI: 10.1371/journal.pgen.1003599] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 05/16/2013] [Indexed: 12/22/2022] Open
Abstract
DNA ligase IV (Dnl4 in budding yeast) is a specialized ligase used in non-homologous end joining (NHEJ) of DNA double-strand breaks (DSBs). Although point and truncation mutations arise in the human ligase IV syndrome, the roles of Dnl4 in DSB repair have mainly been examined using gene deletions. Here, Dnl4 catalytic point mutants were generated that were severely defective in auto-adenylation in vitro and NHEJ activity in vivo, despite being hyper-recruited to DSBs and supporting wild-type levels of Lif1 interaction and assembly of a Ku- and Lif1-containing complex at DSBs. Interestingly, residual levels of especially imprecise NHEJ were markedly higher in a deletion-based assay with Dnl4 catalytic mutants than with a gene deletion strain, suggesting a role of DSB-bound Dnl4 in supporting a mode of NHEJ catalyzed by a different ligase. Similarly, next generation sequencing of repair joints in a distinct single-DSB assay showed that dnl4-K466A mutation conferred a significantly different imprecise joining profile than wild-type Dnl4 and that such repair was rarely observed in the absence of Dnl4. Enrichment of DNA ligase I (Cdc9 in yeast) at DSBs was observed in wild-type as well as dnl4 point mutant strains, with both Dnl4 and Cdc9 disappearing from DSBs upon 5' resection that was unimpeded by the presence of catalytically inactive Dnl4. These findings indicate that Dnl4 can promote mutagenic end joining independently of its catalytic activity, likely by a mechanism that involves Cdc9.
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Affiliation(s)
- Kishore K. Chiruvella
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Zhuobin Liang
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan Ann Arbor, Michigan, United States of America
| | - Shanda R. Birkeland
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Venkatesha Basrur
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Thomas E. Wilson
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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36
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Chiruvella KK, Liang Z, Wilson TE. Repair of double-strand breaks by end joining. Cold Spring Harb Perspect Biol 2013; 5:a012757. [PMID: 23637284 DOI: 10.1101/cshperspect.a012757] [Citation(s) in RCA: 279] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nonhomologous end joining (NHEJ) refers to a set of genome maintenance pathways in which two DNA double-strand break (DSB) ends are (re)joined by apposition, processing, and ligation without the use of extended homology to guide repair. Canonical NHEJ (c-NHEJ) is a well-defined pathway with clear roles in protecting the integrity of chromosomes when DSBs arise. Recent advances have revealed much about the identity, structure, and function of c-NHEJ proteins, but many questions exist regarding their concerted action in the context of chromatin. Alternative NHEJ (alt-NHEJ) refers to more recently described mechanism(s) that repair DSBs in less-efficient backup reactions. There is great interest in defining alt-NHEJ more precisely, including its regulation relative to c-NHEJ, in light of evidence that alt-NHEJ can execute chromosome rearrangements. Progress toward these goals is reviewed.
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37
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Park YB, Chae J, Kim YC, Cho Y. Crystal structure of human Mre11: understanding tumorigenic mutations. Structure 2012; 19:1591-602. [PMID: 22078559 DOI: 10.1016/j.str.2011.09.010] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 09/09/2011] [Accepted: 09/10/2011] [Indexed: 11/29/2022]
Abstract
Mre11 plays an important role in repairing damaged DNA by cleaving broken ends and by providing a platform for other DNA repair proteins. Various Mre11 mutations have been identified in several types of cancer. We have determined the crystal structure of the human Mre11 core (hMre11), which contains the nuclease and capping domains. hMre11 dimerizes through the interfaces between loop β3-α3 from one Mre11 and loop β4-β5 from another Mre11, and between loop α2-β3 from one Mre11 and helices α2 and α3 from another Mre11, and assembles into a completely different dimeric architecture compared with bacterial or archaeal Mre11 homologs. Nbs1 binds to the region containing loop α2-β3 which participates in dimerization. The hMre11 structure in conjunction with biochemical analyses reveals that many tumorigenic mutations are primarily associated with Nbs1 binding and partly with nuclease activities, providing a framework for understanding how mutations inactivate Mre11.
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Affiliation(s)
- Young Bong Park
- Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, South Korea
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38
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Majka J, Alford B, Ausio J, Finn RM, McMurray CT. ATP hydrolysis by RAD50 protein switches MRE11 enzyme from endonuclease to exonuclease. J Biol Chem 2011; 287:2328-41. [PMID: 22102415 DOI: 10.1074/jbc.m111.307041] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MRE11-RAD50 is a key early response protein for processing DNA ends of broken chromosomes for repair, yet how RAD50 nucleotide dynamics regulate MRE11 nuclease activity is poorly understood. We report here that ATP binding and ATP hydrolysis cause a striking butterfly-like opening and closing of the RAD50 subunits, and each structural state has a dramatic functional effect on MRE11. RAD50-MRE11 has an extended conformation in solution when MRE11 is an active nuclease. However, ATP binding to RAD50 induces a closed conformation, and in this state MRE11 is an endonuclease. ATP hydrolysis opens the RAD50-MRE11 complex, and MRE11 maintains exonuclease activity. Thus, ATP hydrolysis is a molecular switch that converts MRE11 from an endonuclease to an exonuclease. We propose a testable model in which the open-closed transitions are used by RAD50-MRE11 to discriminate among DNA ends and drive the choice of recombination pathways.
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Affiliation(s)
- Jerzy Majka
- Lawrence Berkeley National Laboratory, Life Sciences Division, Berkeley, California 94720, USA
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Grob P, Zhang TT, Hannah R, Yang H, Hefferin ML, Tomkinson AE, Nogales E. Electron microscopy visualization of DNA-protein complexes formed by Ku and DNA ligase IV. DNA Repair (Amst) 2011; 11:74-81. [PMID: 22088982 DOI: 10.1016/j.dnarep.2011.10.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 10/13/2011] [Accepted: 10/19/2011] [Indexed: 10/15/2022]
Abstract
The repair of DNA double-stranded breaks (DSBs) is essential for cell viability and genome stability. Aberrant repair of DSBs has been linked with cancer predisposition and aging. During the repair of DSBs by non-homologous end joining (NHEJ), DNA ends are brought together, processed and then joined. In eukaryotes, this repair pathway is initiated by the binding of the ring-shaped Ku heterodimer and completed by DNA ligase IV. The DNA ligase IV complex, DNA ligase IV/XRRC4 in humans and Dnl4/Lif1 in yeast, is recruited to DNA ends in vitro and in vivo by an interaction with Ku and, in yeast, Dnl4/Lif1 stabilizes the binding of yKu to in vivo DSBs. Here we have analyzed the interactions of these functionally conserved eukaryotic NHEJ factors with DNA by electron microscopy. As expected, the ring-shaped Ku complex bound stably and specifically to DNA ends at physiological salt concentrations. At a ratio of 1 Ku molecule per DNA end, the majority of DNA ends were occupied by a single Ku complex with no significant formation of linear DNA multimers or circular loops. Both Dnl4/Lif1 and DNA ligase IV/XRCC4 formed complexes with Ku-bound DNA ends, resulting in intra- and intermolecular DNA end bridging, even with non-ligatable DNA ends. Together, these studies, which provide the first visualization of the conserved complex formed by Ku and DNA ligase IV at juxtaposed DNA ends by electron microscopy, suggest that the DNA ligase IV complex mediates end-bridging by engaging two Ku-bound DNA ends.
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Affiliation(s)
- Patricia Grob
- Howard Hughes Medical Institute, UC Berkeley, CA 94720-3220, United States
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40
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DNA binding proteins: outline of functional classification. Biomol Concepts 2011; 2:293-303. [DOI: 10.1515/bmc.2011.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 05/23/2011] [Indexed: 01/12/2023] Open
Abstract
AbstractDNA-binding proteins composed of DNA-binding domains directly affect genomic functions, mainly by performing transcription, DNA replication or DNA repair. Here, we briefly describe the DNA-binding proteins according to these three major functions. Transcription factors that usually bind to specific sequences of DNA could be classified based on their sequence similarity and the structure of the DNA-binding domains, such as basic, zinc-coordinating, helix-turn-helix domains, etc. Most DNA replication factors do not need a specific sequence of DNA, but instead mainly depend on a DNA structure, with the exception of the origin recognition complex in yeast or Escherichia coli that recognizes the DNA sequences at particular origins. DNA replication includes initiation and elongation. The major DNA-binding proteins involved in these two steps are briefly described. DNA repair proteins bound to DNA depend on the damaged DNA structure. They are classified to base excision repair, DNA mismatch repair, nucleotide excision repair, homologous recombination repair and non-homologous end joining. The major DNA-binding proteins involved in these pathways are briefly described. Histone and high mobility group are two examples of DNA-binding proteins that do not belong to the three categories above and are briefly described. Finally, we warn that the non-specific binding proteins might have an affinity to some non-specific medium materials such as protein A or G beads that are commonly used for immune precipitation, which can easily generate false positive signals while detecting protein-protein interaction; therefore, the results need to be carefully analyzed using positive/negative controls.
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41
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Polo SE, Jackson SP. Dynamics of DNA damage response proteins at DNA breaks: a focus on protein modifications. Genes Dev 2011; 25:409-33. [PMID: 21363960 DOI: 10.1101/gad.2021311] [Citation(s) in RCA: 837] [Impact Index Per Article: 64.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Genome integrity is constantly monitored by sophisticated cellular networks, collectively termed the DNA damage response (DDR). A common feature of DDR proteins is their mobilization in response to genotoxic stress. Here, we outline how the development of various complementary methodologies has provided valuable insights into the spatiotemporal dynamics of DDR protein assembly/disassembly at sites of DNA strand breaks in eukaryotic cells. Considerable advances have also been made in understanding the underlying molecular mechanisms for these events, with post-translational modifications of DDR factors being shown to play prominent roles in controlling the formation of foci in response to DNA-damaging agents. We review these regulatory mechanisms and discuss their biological significance to the DDR.
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Affiliation(s)
- Sophie E Polo
- The Gurdon Institute, Department of Biochemistry, University of Cambridge, Cambridge CB21QN, United Kingdom
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42
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Chen X, Tomkinson AE. Yeast Nej1 is a key participant in the initial end binding and final ligation steps of nonhomologous end joining. J Biol Chem 2010; 286:4931-40. [PMID: 21149442 DOI: 10.1074/jbc.m110.195024] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Saccharomyces cerevisiae, the key components of the nonhomologous end joining (NHEJ) pathway that repairs DNA double-strand breaks (DSBs) are yeast Ku (yKu), Mre11-Rad50-Xrs2, Dnl4-Lif1, and Nej1. Here, we examined the role of Nej1 in NHEJ by a combination of molecular genetic and biochemical approaches. As expected, the recruitment of Nej1 to in vivo DSBs is dependent upon yKu. Surprisingly, Nej1 is required for the stable binding of yKu to in vivo DSBs, in addition to Dnl4-Lif1. Thus, Nej1 and Dnl4-Lif1 are independently recruited by yKu to in vivo DSBs, forming a stable ternary complex that channels DSBs into the NHEJ pathway. In accord with these results, purified Nej1 interacts with yKu and preferentially binds to DNA ends bound by yKu. Furthermore, the binding of a mixture of Nej1 and Dnl4-Lif1 to DNA ends bound by yKu is greater than the sum of the binding of the individual proteins, indicating that pairwise interactions among yKu, Nej1, and Dnl4-Lif1 contribute to complex assembly at DNA ends. Nej1 stimulates intermolecular ligation by Dnl4-Lif1, but, more interestingly, the addition of Nej1 results in more than one intermolecular ligation per Dnl4 molecule. Thus, Nej1 not only plays an important role in determining repair pathway choice by participating in the initial NHEJ complex formed at DSBs but also contributes to the reactivation of Dnl4-Lif1 after repair is complete, thereby increasing the capacity of the NHEJ repair pathway.
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Affiliation(s)
- Xi Chen
- Radiation Oncology Research Laboratory, Department of Radiation Oncology, and The Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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43
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Longhese MP, Bonetti D, Manfrini N, Clerici M. Mechanisms and regulation of DNA end resection. EMBO J 2010; 29:2864-74. [PMID: 20647996 DOI: 10.1038/emboj.2010.165] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 06/28/2010] [Indexed: 02/07/2023] Open
Abstract
DNA double-strand breaks (DSBs) are highly hazardous for genome integrity, because failure to repair these lesions can lead to genomic instability. DSBs can arise accidentally at unpredictable locations into the genome, but they are also normal intermediates in meiotic recombination. Moreover, the natural ends of linear chromosomes resemble DSBs. Although intrachromosomal DNA breaks are potent stimulators of the DNA damage response, the natural ends of linear chromosomes are packaged into protective structures called telomeres that suppress DNA repair/recombination activities. Although DSBs and telomeres are functionally different, they both undergo 5'-3' nucleolytic degradation of DNA ends, a process known as resection. The resulting 3'-single-stranded DNA overhangs enable repair of DSBs by homologous recombination (HR), whereas they allow the action of telomerase at telomeres. The molecular activities required for DSB and telomere end resection are similar, indicating that the initial steps of HR and telomerase-mediated elongation are related. Resection of both DSBs and telomeres must be tightly regulated in time and space to ensure genome stability and cell survival.
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Affiliation(s)
- Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Piazza della Scienza, Milan, Italy.
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44
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Dodson GE, Limbo O, Nieto D, Russell P. Phosphorylation-regulated binding of Ctp1 to Nbs1 is critical for repair of DNA double-strand breaks. Cell Cycle 2010; 9:1516-22. [PMID: 20421724 DOI: 10.4161/cc.9.8.11260] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Repair of DNA double-strand breaks (DSBs) is critical for cell survival and for maintaining genome stability in eukaryotes. In Schizosaccharomyces pombe, the Mre11-Rad50-Nbs1 (MRN) complex and Ctp1 cooperate to perform the initial steps that process and repair these DNA lesions via homologous recombination (HR). While Ctp1 is recruited to DSBs in an MRN-dependent manner, the specific mechanism of this process remained unclear. We recently found that Ctp1 is phosphorylated on a domain rich in putative Casein kinase 2 (CK2) phosphoacceptor sites that resembles the SDTD repeats of Mdc1. Furthermore, phosphorylation of this motif is required for interaction with the FHA domain of Nbs1 that localizes Ctp1 to DSB sites. Here, we review and discuss these findings, and we present new data that further characterize the cellular consequences of mutating CK2 phosphorylation motifs of Ctp1, including data showing that these sites are critical for meiosis.
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Affiliation(s)
- Gerald E Dodson
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA, USA
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45
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Rupnik A, Lowndes NF, Grenon M. MRN and the race to the break. Chromosoma 2010; 119:115-35. [PMID: 19862546 DOI: 10.1007/s00412-009-0242-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 09/12/2009] [Accepted: 09/21/2009] [Indexed: 10/20/2022]
Abstract
In all living cells, DNA is constantly threatened by both endogenous and exogenous agents. In order to protect genetic information, all cells have developed a sophisticated network of proteins, which constantly monitor genomic integrity. This network, termed the DNA damage response, senses and signals the presence of DNA damage to effect numerous biological responses, including DNA repair, transient cell cycle arrests ("checkpoints") and apoptosis. The MRN complex (MRX in yeast), composed of Mre11, Rad50 and Nbs1 (Xrs2), is a key component of the immediate early response to DNA damage, involved in a cross-talk between the repair and checkpoint machinery. Using its ability to bind DNA ends, it is ideally placed to sense and signal the presence of double strand breaks and plays an important role in DNA repair and cellular survival. Here, we summarise recent observation on MRN structure, function, regulation and emerging mechanisms by which the MRN nano-machinery protects genomic integrity. Finally, we discuss the biological significance of the unique MRN structure and summarise the emerging sequence of early events of the response to double strand breaks orchestrated by the MRN complex.
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Affiliation(s)
- Agnieszka Rupnik
- Centre for Chromosome Biology, School of Natural Science, National University of Ireland Galway, University Road, Galway, Ireland
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46
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Current World Literature. Curr Opin Allergy Clin Immunol 2009; 9:574-8. [DOI: 10.1097/aci.0b013e328333c13c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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47
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Lloyd J, Chapman JR, Clapperton JA, Haire LF, Hartsuiker E, Li J, Carr AM, Jackson SP, Smerdon SJ. A supramodular FHA/BRCT-repeat architecture mediates Nbs1 adaptor function in response to DNA damage. Cell 2009; 139:100-11. [PMID: 19804756 PMCID: PMC2900601 DOI: 10.1016/j.cell.2009.07.043] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 06/08/2009] [Accepted: 07/22/2009] [Indexed: 10/20/2022]
Abstract
The Mre11/Rad50/Nbs1 protein complex plays central enzymatic and signaling roles in the DNA-damage response. Nuclease (Mre11) and scaffolding (Rad50) components of MRN have been extensively characterized, but the molecular basis of Nbs1 function has remained elusive. Here, we present a 2.3A crystal structure of the N-terminal region of fission yeast Nbs1, revealing an unusual but conserved architecture in which the FHA- and BRCT-repeat domains structurally coalesce. We demonstrate that diphosphorylated pSer-Asp-pThr-Asp motifs, recently identified as multicopy docking sites within Mdc1, are evolutionarily conserved Nbs1 binding targets. Furthermore, we show that similar phosphomotifs within Ctp1, the fission yeast ortholog of human CtIP, promote interactions with the Nbs1 FHA domain that are necessary for Ctp1-dependent resistance to DNA damage. Finally, we establish that human Nbs1 interactions with Mdc1 occur through both its FHA- and BRCT-repeat domains, suggesting how their structural and functional interdependence underpins Nbs1 adaptor functions in the DNA-damage response.
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Affiliation(s)
- Janette Lloyd
- MRC National Institute for Medical Research, Division of Molecular Structure, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - J. Ross Chapman
- The Gurdon Institute and Department of Zoology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Julie A. Clapperton
- MRC National Institute for Medical Research, Division of Molecular Structure, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Lesley F. Haire
- MRC National Institute for Medical Research, Division of Molecular Structure, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Edgar Hartsuiker
- Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, UK
| | - Jiejin Li
- MRC National Institute for Medical Research, Division of Molecular Structure, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Antony M. Carr
- Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, UK
| | - Stephen P. Jackson
- The Gurdon Institute and Department of Zoology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Stephen J. Smerdon
- MRC National Institute for Medical Research, Division of Molecular Structure, The Ridgeway, Mill Hill, London NW7 1AA, UK
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48
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Williams RS, Dodson GE, Limbo O, Yamada Y, Williams JS, Guenther G, Classen S, Glover JM, Iwasaki H, Russell P, Tainer JA. Nbs1 flexibly tethers Ctp1 and Mre11-Rad50 to coordinate DNA double-strand break processing and repair. Cell 2009; 139:87-99. [PMID: 19804755 PMCID: PMC2762657 DOI: 10.1016/j.cell.2009.07.033] [Citation(s) in RCA: 248] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 05/14/2009] [Accepted: 07/10/2009] [Indexed: 11/30/2022]
Abstract
The Nijmegen breakage syndrome 1 (Nbs1) subunit of the Mre11-Rad50-Nbs1 (MRN) complex protects genome integrity by coordinating double-strand break (DSB) repair and checkpoint signaling through undefined interactions with ATM, MDC1, and Sae2/Ctp1/CtIP. Here, fission yeast and human Nbs1 structures defined by X-ray crystallography and small angle X-ray scattering (SAXS) reveal Nbs1 cardinal features: fused, extended, FHA-BRCT(1)-BRCT(2) domains flexibly linked to C-terminal Mre11- and ATM-binding motifs. Genetic, biochemical, and structural analyses of an Nbs1-Ctp1 complex show Nbs1 recruits phosphorylated Ctp1 to DSBs via binding of the Nbs1 FHA domain to a Ctp1 pThr-Asp motif. Nbs1 structures further identify an extensive FHA-BRCT interface, a bipartite MDC1-binding scaffold, an extended conformational switch, and the molecular consequences associated with cancer predisposing Nijmegen breakage syndrome mutations. Tethering of Ctp1 to a flexible Nbs1 arm suggests a mechanism for restricting DNA end processing and homologous recombination activities of Sae2/Ctp1/CtIP to the immediate vicinity of DSBs.
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Affiliation(s)
- R. Scott Williams
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
- Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
| | - Gerald E. Dodson
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
| | - Oliver Limbo
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
| | - Yoshiki Yamada
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
| | - Jessica S. Williams
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
| | - Grant Guenther
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
- Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
| | - Scott Classen
- Life Sciences Division, Department of Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - J.N. Mark Glover
- Department of Biochemistry, 4-74 Medical Sciences Building, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Hiroshi Iwasaki
- Division of Molecular and Cellular Biology, International Graduate School of Arts and Sciences, Yokohama City University, Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Paul Russell
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
| | - John A. Tainer
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
- Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB4, La Jolla, CA 92037, USA
- Life Sciences Division, Department of Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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49
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50
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Zhang Y, Shim EY, Davis M, Lee SE. Regulation of repair choice: Cdk1 suppresses recruitment of end joining factors at DNA breaks. DNA Repair (Amst) 2009; 8:1235-41. [PMID: 19699692 DOI: 10.1016/j.dnarep.2009.07.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 07/19/2009] [Accepted: 07/21/2009] [Indexed: 11/16/2022]
Abstract
Cell cycle plays a crucial role in regulating the pathway used to repair DNA double-strand breaks (DSBs). In Saccharomyces cerevisiae, homologous recombination is primarily limited to non-G(1) cells as the formation of recombinogenic single-stranded DNA requires CDK1-dependent 5' to 3' resection of DNA ends. However, the effect of cell cycle on non-homologous end joining (NHEJ) is not yet clearly defined. Using an assay to quantitatively measure the contributions of each repair pathway to repair product formation and cellular survival after DSB induction, we found that NHEJ is most efficient at G(1), and markedly repressed at G(2). Repression of NHEJ at G(2) is achieved by efficient end resection and by the reduced association of core NHEJ proteins with DNA breaks, both of which depend on the CDK1 activity. Importantly, repression of 5' end resection by CDK1 inhibition at G(2) alone did not fully restore either physical association of Ku/Dnl4-Lif1 with DSBs or NHEJ proficiency to the level at G(1). Expression of excess Ku can partially offset the inhibition of end joining at G(2). The results suggest that regulation of Ku/Dnl4-Lif1 affinity for DNA ends may contribute to the cell cycle-dependent modulation of NHEJ efficiency.
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Affiliation(s)
- Yu Zhang
- Department of Molecular Medicine and Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 78245, United States
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