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Vaculíková J, Holá M, Králová B, Lelkes E, Štefanovie B, Vágnerová R, Angelis KJ, Paleček JJ. NSE5 subunit interacts with distant regions of the SMC arms in the Physcomitrium patens SMC5/6 complex. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024. [PMID: 38858852 DOI: 10.1111/tpj.16869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 05/21/2024] [Accepted: 05/25/2024] [Indexed: 06/12/2024]
Abstract
Structural maintenance of chromosome (SMC) complexes play roles in cohesion, condensation, replication, transcription, and DNA repair. Their cores are composed of SMC proteins with a unique structure consisting of an ATPase head, long arm, and hinge. SMC complexes form long rod-like structures, which can change to ring-like and elbow-bent conformations upon binding ATP, DNA, and other regulatory factors. These SMC dynamic conformational changes are involved in their loading, translocation, and DNA loop extrusion. Here, we examined the binding and role of the PpNSE5 regulatory factor of Physcomitrium patens PpSMC5/6 complex. We found that the PpNSE5 C-terminal half (aa230-505) is required for binding to its PpNSE6 partner, while the N-terminal half (aa1-230) binds PpSMC subunits. Specifically, the first 71 amino acids of PpNSE5 were required for binding to PpSMC6. Interestingly, the PpNSE5 binding required the PpSMC6 head-proximal joint region and PpSMC5 hinge-proximal arm, suggesting a long distance between binding sites on PpSMC5 and PpSMC6 arms. Therefore, we hypothesize that PpNSE5 either links two antiparallel SMC5/6 complexes or binds one SMC5/6 in elbow-bent conformation, the later model being consistent with the role of NSE5/NSE6 dimer as SMC5/6 loading factor to DNA lesions. In addition, we generated the P. patens Ppnse5KO1 mutant line with an N-terminally truncated version of PpNSE5, which exhibited DNA repair defects while keeping a normal number of rDNA repeats. As the first 71 amino acids of PpNSE5 are required for PpSMC6 binding, our results suggest the role of PpNSE5-PpSMC6 interaction in SMC5/6 loading to DNA lesions.
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Affiliation(s)
- Jitka Vaculíková
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - Marcela Holá
- Institute of Experimental Botany Czech Academy of Sciences, Na Karlovce 1, 16000, Prague, Czech Republic
| | - Barbora Králová
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - Edit Lelkes
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - Barbora Štefanovie
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - Radka Vágnerová
- Institute of Experimental Botany Czech Academy of Sciences, Na Karlovce 1, 16000, Prague, Czech Republic
| | - Karel J Angelis
- Institute of Experimental Botany Czech Academy of Sciences, Na Karlovce 1, 16000, Prague, Czech Republic
| | - Jan J Paleček
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
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2
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Zhao X, Wan B, Guan D, Li S, Chwat-Edelstein T. The Mms22-Rtt107 axis dampens the DNA damage checkpoint by reducing the stability of the Rad9 checkpoint mediator. RESEARCH SQUARE 2024:rs.3.rs-4417144. [PMID: 38826278 PMCID: PMC11142307 DOI: 10.21203/rs.3.rs-4417144/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
The DNA damage checkpoint is a highly conserved signaling pathway induced by genotoxin exposure or endogenous genome stress. It alters many cellular processes such as arresting the cell cycle progression and increasing DNA repair capacities. However, cells can downregulate the checkpoint after prolonged stress exposure to allow continued growth and alternative repair. Strategies that can dampen the DNA damage checkpoint are not well understood. Here, we report that budding yeast employs a pathway composed of the scaffold protein Rtt107, its binding partner Mms22, and an Mms22-associated ubiquitin ligase complex to downregulate the DNA damage checkpoint. Mechanistically, this pathway promotes the proteasomal degradation of a key checkpoint factor, Rad9. Furthermore, Rtt107 binding to Mms22 helps to enrich the ubiquitin ligase complex on chromatin and target the chromatin-bound form of Rad9. Finally, we provide evidence that the Rtt107-Mms22 axis operates in parallel with the Rtt107-Slx4 axis, which displaces Rad9 from chromatin. We thus propose that Rtt107 enables a bifurcated "anti-Rad9" strategy to optimally downregulate the DNA damage checkpoint.
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Affiliation(s)
| | | | | | - Shibai Li
- Memorial Sloan Kettering Cancer Center
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3
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Huang W, Qiu F, Zheng L, Shi M, Shen M, Zhao X, Xiang S. Structural insights into Rad18 targeting by the SLF1 BRCT domains. J Biol Chem 2023; 299:105288. [PMID: 37748650 PMCID: PMC10598736 DOI: 10.1016/j.jbc.2023.105288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 09/18/2023] [Accepted: 09/20/2023] [Indexed: 09/27/2023] Open
Abstract
Rad18 interacts with the SMC5/6 localization factor 1 (SLF1) to recruit the SMC5/6 complex to DNA damage sites for repair. The mechanism of the specific Rad18 recognition by SLF1 is unclear. Here, we present the crystal structure of the tandem BRCT repeat (tBRCT) in SLF1 (SLF1tBRCT) bound with the interacting Rad18 peptide. Our structure and biochemical studies demonstrate that SLF1tBRCT interacts with two phosphoserines and adjacent residues in Rad18 for high-affinity and specificity Rad18 recognition. We found that SLF1tBRCT utilizes mechanisms common among tBRCTs as well as unique ones for Rad18 binding, the latter include interactions with an α-helical structure in Rad18 that has not been observed in other tBRCT-bound ligand proteins. Our work provides structural insights into Rad18 targeting by SLF1 and expands the understanding of BRCT-mediated complex assembly.
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Affiliation(s)
- Wei Huang
- Department of Biochemistry and Molecular Biology, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin, P. R. China
| | - Fangjie Qiu
- Department of Biochemistry and Molecular Biology, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin, P. R. China
| | - Lin Zheng
- Department of Biochemistry and Molecular Biology, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin, P. R. China
| | - Meng Shi
- Department of Biochemistry and Molecular Biology, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin, P. R. China
| | - Miaomiao Shen
- National Clinical Research Center for Cancer, Tianjin Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, P. R. China
| | - Xiaolan Zhao
- Department of Molecular Biology, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Song Xiang
- Department of Biochemistry and Molecular Biology, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin, P. R. China.
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4
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Vladejić J, Yang F, Dvořák Tomaštíková E, Doležel J, Palecek JJ, Pecinka A. Analysis of BRCT5 domain-containing proteins reveals a new component of DNA damage repair in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2022; 13:1023358. [PMID: 36578335 PMCID: PMC9791218 DOI: 10.3389/fpls.2022.1023358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 11/14/2022] [Indexed: 06/17/2023]
Abstract
The integrity of plant genetic information is constantly challenged by various internal and external factors. Therefore, plants use a sophisticated molecular network to identify, signal and repair damaged DNA. Here, we report on the identification and analysis of four uncharacterized Arabidopsis BRCT5 DOMAIN CONTAINING PROTEINs (BCPs). Proteins with the BRCT5 domain are frequently involved in the maintenance of genome stability across eukaryotes. The screening for sensitivity to induced DNA damage identified BCP1 as the most interesting candidate. We show that BCP1 loss of function mutants are hypersensitive to various types of DNA damage and accumulate an increased number of dead cells in root apical meristems upon DNA damage. Analysis of publicly available sog1 transcriptomic and SOG1 genome-wide DNA binding data revealed that BCP1 is inducible by gamma radiation and is a direct target of this key DNA damage signaling transcription factor. Importantly, bcp1 plants showed a reduced frequency of somatic homologous recombination in response to both endogenous and induced DNA damage. Altogether, we identified a novel plant-specific DNA repair factor that acts downstream of SOG1 in homology-based repair.
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Affiliation(s)
- Jovanka Vladejić
- Institute of Experimental Botany (IEB), Czech Acad Sci, Centre of the Region Haná for Biotechnological and Agricultural Research (CRH), Olomouc, Czechia
| | - Fen Yang
- Institute of Experimental Botany (IEB), Czech Acad Sci, Centre of the Region Haná for Biotechnological and Agricultural Research (CRH), Olomouc, Czechia
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czechia
| | - Eva Dvořák Tomaštíková
- Institute of Experimental Botany (IEB), Czech Acad Sci, Centre of the Region Haná for Biotechnological and Agricultural Research (CRH), Olomouc, Czechia
| | - Jaroslav Doležel
- Institute of Experimental Botany (IEB), Czech Acad Sci, Centre of the Region Haná for Biotechnological and Agricultural Research (CRH), Olomouc, Czechia
| | - Jan J. Palecek
- National Centre for Biomolecular Research (NCBR), Faculty of Science, Masaryk University, Brno, Czechia
| | - Ales Pecinka
- Institute of Experimental Botany (IEB), Czech Acad Sci, Centre of the Region Haná for Biotechnological and Agricultural Research (CRH), Olomouc, Czechia
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czechia
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5
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Zhu H, Wu Z, Ding X, Post MJ, Guo R, Wang J, Wu J, Tang W, Ding S, Zhou G. Production of cultured meat from pig muscle stem cells. Biomaterials 2022; 287:121650. [PMID: 35872554 DOI: 10.1016/j.biomaterials.2022.121650] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 05/13/2022] [Accepted: 06/22/2022] [Indexed: 11/02/2022]
Abstract
Cultured meat is meat for consumption produced in a more sustainable way. It involves cell harvesting and expansion, differentiation into myotubes, construction into muscle fibres and meat structuring. We isolated 5.3 × 104 porcine muscle stem cells from 1 g of neonatal pig muscle tissue. According to calculations, we need to expand muscle stem cells 106-107 times to produce 100 g or 1 kg of cultured meat. However, the cells gradually lost the ability to express stemness and mature muscle cell markers (PAX7, MyHC). To tackle this critical issue and maintain cell function during cell expansion, we found that long-term culture with (100 μM) l-Ascorbic acid 2-phosphate (Asc-2P) accelerated cell proliferation while preserving the muscle cell differentiation. We further optimized a scalable PDMS mold. Porcine muscle stem cells formed structurally-organized myotubes similar to muscle fibres in the mold. Asc-2P enhanced porcine muscle cells grown as 3D tissue networks that can produce a relatively large 3D tissue networks as cultured meat building blocks, which showed improved texture and amino acid content. These results established a realistic workflow for the production of cultured meat that mimics the pork meat structurally and is potentially scalable for industry.
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Affiliation(s)
- Haozhe Zhu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China; National Center of Meat Quality and Safety Control, MOST; Key Laboratory of Meat Processing and Quality Control, MOE; Key Laboratory of Meat Processing, MOA, Nanjing Agricultural University, 210095, Jiangsu, China
| | - Zhongyuan Wu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China; National Center of Meat Quality and Safety Control, MOST; Key Laboratory of Meat Processing and Quality Control, MOE; Key Laboratory of Meat Processing, MOA, Nanjing Agricultural University, 210095, Jiangsu, China
| | - Xi Ding
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China; National Center of Meat Quality and Safety Control, MOST; Key Laboratory of Meat Processing and Quality Control, MOE; Key Laboratory of Meat Processing, MOA, Nanjing Agricultural University, 210095, Jiangsu, China
| | - Mark J Post
- Department of Physiology, Maastricht University, CARIM, Maastricht, the Netherlands
| | - Renpeng Guo
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China
| | - Jie Wang
- College of Artificial Intelligence, Nanjing Agricultural University, Nanjing, 210031, China
| | - Junjun Wu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China
| | - Wenlai Tang
- School of Electrical and Automation Engineering, and Jiangsu Key Laboratory of 3D Printing Equipment and Manufacturing, Nanjing Normal University, Nanjing, 210023, China; State Key Laboratory of Pharmaceutical Biotechnology, Department of Sports Medicine and Adult Reconstructive Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.
| | - Shijie Ding
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China; National Center of Meat Quality and Safety Control, MOST; Key Laboratory of Meat Processing and Quality Control, MOE; Key Laboratory of Meat Processing, MOA, Nanjing Agricultural University, 210095, Jiangsu, China.
| | - Guanghong Zhou
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China; National Center of Meat Quality and Safety Control, MOST; Key Laboratory of Meat Processing and Quality Control, MOE; Key Laboratory of Meat Processing, MOA, Nanjing Agricultural University, 210095, Jiangsu, China.
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6
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Day M, Oliver AW, Pearl LH. Phosphorylation-dependent assembly of DNA damage response systems and the central roles of TOPBP1. DNA Repair (Amst) 2021; 108:103232. [PMID: 34678589 PMCID: PMC8651625 DOI: 10.1016/j.dnarep.2021.103232] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 11/11/2022]
Abstract
The cellular response to DNA damage (DDR) that causes replication collapse and/or DNA double strand breaks, is characterised by a massive change in the post-translational modifications (PTM) of hundreds of proteins involved in the detection and repair of DNA damage, and the communication of the state of damage to the cellular systems that regulate replication and cell division. A substantial proportion of these PTMs involve targeted phosphorylation, which among other effects, promotes the formation of multiprotein complexes through the specific binding of phosphorylated motifs on one protein, by specialised domains on other proteins. Understanding the nature of these phosphorylation mediated interactions allows definition of the pathways and networks that coordinate the DDR, and helps identify new targets for therapeutic intervention that may be of benefit in the treatment of cancer, where DDR plays a key role. In this review we summarise the present understanding of how phosphorylated motifs are recognised by BRCT domains, which occur in many DDR proteins. We particularly focus on TOPBP1 - a multi-BRCT domain scaffold protein with essential roles in replication and the repair and signalling of DNA damage.
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Affiliation(s)
- Matthew Day
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Antony W Oliver
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Laurence H Pearl
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK; Division of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW1E 6BT, UK.
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7
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Hallett ST, Schellenberger P, Zhou L, Beuron F, Morris E, Murray JM, Oliver AW. Nse5/6 is a negative regulator of the ATPase activity of the Smc5/6 complex. Nucleic Acids Res 2021; 49:4534-4549. [PMID: 33849072 PMCID: PMC8096239 DOI: 10.1093/nar/gkab234] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 12/13/2022] Open
Abstract
The multi-component Smc5/6 complex plays a critical role in the resolution of recombination intermediates formed during mitosis and meiosis, and in the cellular response to replication stress. Using recombinant proteins, we have reconstituted a series of defined Saccharomyces cerevisiae Smc5/6 complexes, visualised them by negative stain electron microscopy, and tested their ability to function as an ATPase. We find that only the six protein ‘holo-complex’ is capable of turning over ATP and that its activity is significantly increased by the addition of double-stranded DNA to reaction mixes. Furthermore, stimulation is wholly dependent on functional ATP-binding pockets in both Smc5 and Smc6. Importantly, we demonstrate that budding yeast Nse5/6 acts as a negative regulator of Smc5/6 ATPase activity, binding to the head-end of the complex to suppress turnover, irrespective of the DNA-bound status of the complex.
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Affiliation(s)
- Stephen T Hallett
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK
| | - Pascale Schellenberger
- Electron Microscopy Imaging Centre, School of Life Sciences, University of Sussex, Falmer, UK
| | - Lihong Zhou
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK
| | | | - Ed Morris
- The Institute of Cancer Research, London, UK
| | - Johanne M Murray
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK
| | - Antony W Oliver
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK
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8
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9
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Wan B, Wu J, Meng X, Lei M, Zhao X. Molecular Basis for Control of Diverse Genome Stability Factors by the Multi-BRCT Scaffold Rtt107. Mol Cell 2019; 75:238-251.e5. [PMID: 31348879 PMCID: PMC6745058 DOI: 10.1016/j.molcel.2019.05.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/11/2019] [Accepted: 05/30/2019] [Indexed: 01/08/2023]
Abstract
BRCT domains support myriad protein-protein interactions involved in genome maintenance. Although di-BRCT recognition of phospho-proteins is well known to support the genotoxic response, whether multi-BRCT domains can acquire distinct structures and functions is unclear. Here we present the tetra-BRCT structures from the conserved yeast protein Rtt107 in free and ligand-bound forms. The four BRCT repeats fold into a tetrahedral structure that recognizes unmodified ligands using a bi-partite mechanism, suggesting repeat origami enabling function acquisition. Functional studies show that Rtt107 binding of partner proteins of diverse activities promotes genome replication and stability in both distinct and concerted manners. A unified theme is that tetra- and di-BRCT domains of Rtt107 collaborate to recruit partner proteins to chromatin. Our work thus illustrates how a master regulator uses two types of BRCT domains to recognize distinct genome factors and direct them to chromatin for constitutive genome protection.
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Affiliation(s)
- Bingbing Wan
- Molecular Biology Department, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Jian Wu
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
| | - Xiangzhou Meng
- Molecular Biology Department, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Ming Lei
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China; Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China; National Facility for Protein Science in Shanghai, Zhangjiang Lab, Shanghai 201210, China; Shanghai Science Research Center, Chinese Academy of Sciences, Shanghai 201204, China.
| | - Xiaolan Zhao
- Molecular Biology Department, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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10
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Phospho-peptide binding domains in S. cerevisiae model organism. Biochimie 2019; 163:117-127. [PMID: 31194995 DOI: 10.1016/j.biochi.2019.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 06/06/2019] [Indexed: 02/07/2023]
Abstract
Protein phosphorylation is one of the main mechanisms by which signals are transmitted in eukaryotic cells, and it plays a crucial regulatory role in almost all cellular processes. In yeast, more than half of the proteins are phosphorylated in at least one site, and over 20,000 phosphopeptides have been experimentally verified. However, the functional consequences of these phosphorylation events for most of the identified phosphosites are unknown. A family of protein interaction domains selectively recognises phosphorylated motifs to recruit regulatory proteins and activate signalling pathways. Nine classes of dedicated modules are coded by the yeast genome: 14-3-3, FHA, WD40, BRCT, WW, PBD, and SH2. The recognition specificity relies on a few residues on the target protein and has coevolved with kinase specificity. In the present study, we review the current knowledge concerning yeast phospho-binding domains and their networks. We emphasise the relevance of both positive and negative amino acid selection to orchestrate the highly regulated outcomes of inter- and intra-molecular interactions. Finally, we hypothesise that only a small fraction of yeast phosphorylation events leads to the creation of a docking site on the target molecule, while many have a direct effect on the protein or, as has been proposed, have no function at all.
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11
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Quantitative sensing and signalling of single-stranded DNA during the DNA damage response. Nat Commun 2019; 10:944. [PMID: 30808869 PMCID: PMC6391461 DOI: 10.1038/s41467-019-08889-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 02/05/2019] [Indexed: 12/11/2022] Open
Abstract
The DNA damage checkpoint senses the presence of DNA lesions and controls the cellular response thereto. A crucial DNA damage signal is single-stranded DNA (ssDNA), which is frequently found at sites of DNA damage and recruits the sensor checkpoint kinase Mec1-Ddc2. However, how this signal – and therefore the cell's DNA damage load – is quantified, is poorly understood. Here, we use genetic manipulation of DNA end resection to induce quantitatively different ssDNA signals at a site-specific double strand break in budding yeast and identify two distinct signalling circuits within the checkpoint. The local checkpoint signalling circuit leading to γH2A phosphorylation is unresponsive to increased amounts of ssDNA, while the global checkpoint signalling circuit, which triggers Rad53 activation, integrates the ssDNA signal quantitatively. The global checkpoint signal critically depends on the 9-1-1 and its downstream acting signalling axis, suggesting that ssDNA quantification depends on at least two sensor complexes. DNA damage triggers checkpoint signalling mechanisms. Here the authors reveal differential phosphorylation of targets of the Mec1-Ddc2 checkpoint kinase by analyzing the effect of quantitatively different ssDNA signals.
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12
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Budding yeast Rtt107 prevents checkpoint hyperactivation after replicative stress by limiting DNA damage. DNA Repair (Amst) 2019; 74:1-16. [DOI: 10.1016/j.dnarep.2019.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 12/20/2018] [Accepted: 01/04/2019] [Indexed: 01/08/2023]
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13
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Brc1 Promotes the Focal Accumulation and SUMO Ligase Activity of Smc5-Smc6 during Replication Stress. Mol Cell Biol 2019; 39:MCB.00271-18. [PMID: 30348841 DOI: 10.1128/mcb.00271-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/12/2018] [Indexed: 11/20/2022] Open
Abstract
As genetic instability drives disease or loss of cell fitness, cellular safeguards have evolved to protect the genome, especially during sensitive cell cycle phases, such as DNA replication. Fission yeast Brc1 has emerged as a key factor in promoting cell survival when replication forks are stalled or collapsed. Brc1 is a multi-BRCT protein that is structurally related to the budding yeast Rtt107 and human PTIP DNA damage response factors, but functional similarities appear limited. Brc1 is a dosage suppressor of a mutation in the essential Smc5-Smc6 genome stability complex and is thought to act in a bypass pathway. In this study, we reveal an unexpectedly intimate connection between Brc1 and Smc5-Smc6 function. Brc1 is required for the accumulation of the Smc5-Smc6 genome stability complex in foci during replication stress and for activation of the intrinsic SUMO ligase activity of the complex by collapsed replication forks. Moreover, we show that the chromatin association and SUMO ligase activity of Smc5-Smc6 require the Nse5-Nse6 heterodimer, explaining how this nonessential cofactor critically supports the DNA repair roles of Smc5-Smc6. We also found that Brc1 interacts with Nse5-Nse6, as well as gamma-H2A, so it can tether Smc5-Smc6 at replicative DNA lesions to promote survival.
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14
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Oravcová M, Boddy MN. Recruitment, loading, and activation of the Smc5-Smc6 SUMO ligase. Curr Genet 2019; 65:669-676. [PMID: 30600397 DOI: 10.1007/s00294-018-0922-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 12/14/2018] [Accepted: 12/15/2018] [Indexed: 12/21/2022]
Abstract
Duplication of the genome poses one of the most significant threats to genetic integrity, cellular fitness, and organismal health. Therefore, numerous mechanisms have evolved that maintain replication fork stability in the face of DNA damage and allow faithful genome duplication. The fission yeast BRCT-domain-containing protein Brc1, and its budding yeast orthologue Rtt107, has emerged as a "hub" factor that integrates multiple replication fork protection mechanisms. Notably, the cofactors and pathways through which Brc1, Rtt107, and their human orthologue (PTIP) act have appeared largely distinct. This either represents true evolutionary functional divergence, or perhaps an incomplete genetic and biochemical analysis of each protein. In this regard, we recently showed that like Rtt107, Brc1 supports key functions of the Smc5-Smc6 complex, including its recruitment into DNA repair foci, chromatin association, and SUMO ligase activity. Furthermore, fission yeast cells lacking the Nse5-Nse6 genome stability factor were found to exhibit defects in Smc5-Smc6 function, similar to but more severe than those in cells lacking Brc1. Here, we place these findings in context with the known functions of Brc1, Rtt107, and Smc5-Smc6, present data suggesting a role for acetylation in Smc5-Smc6 chromatin loading, and discuss wider implications for genome stability.
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Affiliation(s)
- Martina Oravcová
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Michael N Boddy
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA, 92037, USA.
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15
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Abstract
The SLX4/FANCP tumor suppressor has emerged as a key player in the maintenance of genome stability, making pivotal contributions to the repair of interstrand cross-links, homologous recombination, and in response to replication stress genome-wide as well as at specific loci such as common fragile sites and telomeres. SLX4 does so in part by acting as a scaffold that controls and coordinates the XPF-ERCC1, MUS81-EME1, and SLX1 structure-specific endonucleases in different DNA repair and recombination mechanisms. It also interacts with other important DNA repair and cell cycle control factors including MSH2, PLK1, TRF2, and TOPBP1 as well as with ubiquitin and SUMO. This review aims at providing an up-to-date and comprehensive view on the key functions that SLX4 fulfills to maintain genome stability as well as to highlight and discuss areas of uncertainty and emerging concepts.
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Affiliation(s)
- Jean-Hugues Guervilly
- a CRCM, CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes , Marseille , France
| | - Pierre Henri Gaillard
- a CRCM, CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes , Marseille , France
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16
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Wilson MD, Durocher D. Reading chromatin signatures after DNA double-strand breaks. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0280. [PMID: 28847817 DOI: 10.1098/rstb.2016.0280] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/18/2017] [Indexed: 12/14/2022] Open
Abstract
DNA double-strand breaks (DSBs) are DNA lesions that must be accurately repaired in order to preserve genomic integrity and cellular viability. The response to DSBs reshapes the local chromatin environment and is largely orchestrated by the deposition, removal and detection of a complex set of chromatin-associated post-translational modifications. In particular, the nucleosome acts as a central signalling hub and landing platform in this process by organizing the recruitment of repair and signalling factors, while at the same time coordinating repair with other DNA-based cellular processes. While current research has provided a descriptive overview of which histone marks affect DSB repair, we are only beginning to understand how these marks are interpreted to foster an efficient DSB response. Here we review how the modified chromatin surrounding DSBs is read, with a focus on the insights gleaned from structural and biochemical studies.This article is part of the themed issue 'Chromatin modifiers and remodellers in DNA repair and signalling'.
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Affiliation(s)
- Marcus D Wilson
- Macromolecular Machines Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Daniel Durocher
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 3E1
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17
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Abstract
DNA replication and homologous recombination involve the formation of branched DNA structures that physically link chromosomes. Such DNA-based connections, which arise during S-phase, are typically disengaged prior to entry into mitosis, in order to ensure proper chromosome segregation. Exceptions can, however, occur: replication stress, or elevated levels of DNA damage, may cause cells to enter mitosis with unfinished replication as well as carrying recombination intermediates, such as Holliday junctions. Hence, cells are equipped with pathways that recognize and process branched DNA structures, and evolved mechanisms to enhance their function when on the verge of undergoing cell division. One of these pathways utilizes the structure-selective endonuclease Mus81, which is thought to facilitate the resolution of replication and recombination intermediates. Mus81 function is known to be enhanced upon entry into M phase in budding yeast and human cells. Based on recent findings, we discuss here an updated model of Mus81 control during the cell cycle.
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Affiliation(s)
- Boris Pfander
- DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Joao Matos
- Institute of Biochemistry, HPM D6.5 - ETH Zürich, Zürich, Switzerland
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18
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Princz LN, Wild P, Bittmann J, Aguado FJ, Blanco MG, Matos J, Pfander B. Dbf4-dependent kinase and the Rtt107 scaffold promote Mus81-Mms4 resolvase activation during mitosis. EMBO J 2017; 36:664-678. [PMID: 28096179 PMCID: PMC5331752 DOI: 10.15252/embj.201694831] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Revised: 12/15/2016] [Accepted: 12/19/2016] [Indexed: 11/29/2022] Open
Abstract
DNA repair by homologous recombination is under stringent cell cycle control. This includes the last step of the reaction, disentanglement of DNA joint molecules (JMs). Previous work has established that JM resolving nucleases are activated specifically at the onset of mitosis. In case of budding yeast Mus81‐Mms4, this cell cycle stage‐specific activation is known to depend on phosphorylation by CDK and Cdc5 kinases. Here, we show that a third cell cycle kinase, Cdc7‐Dbf4 (DDK), targets Mus81‐Mms4 in conjunction with Cdc5—both kinases bind to as well as phosphorylate Mus81‐Mms4 in an interdependent manner. Moreover, DDK‐mediated phosphorylation of Mms4 is strictly required for Mus81 activation in mitosis, establishing DDK as a novel regulator of homologous recombination. The scaffold protein Rtt107, which binds the Mus81‐Mms4 complex, interacts with Cdc7 and thereby targets DDK and Cdc5 to the complex enabling full Mus81 activation. Therefore, Mus81 activation in mitosis involves at least three cell cycle kinases, CDK, Cdc5 and DDK. Furthermore, tethering of the kinases in a stable complex with Mus81 is critical for efficient JM resolution.
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Affiliation(s)
- Lissa N Princz
- Max Planck Institute of Biochemistry, DNA Replication and Genome Integrity, Martinsried, Germany
| | - Philipp Wild
- Institute of Biochemistry, Eidgenössische Technische Hochschule, Zürich, Switzerland
| | - Julia Bittmann
- Max Planck Institute of Biochemistry, DNA Replication and Genome Integrity, Martinsried, Germany
| | - F Javier Aguado
- Department of Biochemistry and Molecular Biology, Center for Research in Molecular Medicine and Chronic Diseases, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Miguel G Blanco
- Department of Biochemistry and Molecular Biology, Center for Research in Molecular Medicine and Chronic Diseases, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Joao Matos
- Institute of Biochemistry, Eidgenössische Technische Hochschule, Zürich, Switzerland
| | - Boris Pfander
- Max Planck Institute of Biochemistry, DNA Replication and Genome Integrity, Martinsried, Germany
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19
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Wan B, Hang LE, Zhao X. Multi-BRCT scaffolds use distinct strategies to support genome maintenance. Cell Cycle 2016; 15:2561-2570. [PMID: 27580271 DOI: 10.1080/15384101.2016.1218102] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Genome maintenance requires coordinated actions of diverse DNA metabolism processes. Scaffolding proteins, such as those containing multiple BRCT domains, can influence these processes by collaborating with numerous partners. The best-studied examples of multi-BRCT scaffolds are the budding yeast Dpb11 and its homologues in other organisms, which regulate DNA replication, repair, and damage checkpoints. Recent studies have shed light on another group of multi-BRCT scaffolds, including Rtt107 in budding yeast and related proteins in other organisms. These proteins also influence several DNA metabolism pathways, though they use strategies unlike those employed by the Dpb11 family of proteins. Yet, at the same time, these 2 classes of multi-BRCT proteins can collaborate under specific situations. This review summarizes recent advances in our understanding of how these multi-BRCT proteins function in distinct manners and how they collaborate, with a focus on Dpb11 and Rtt107.
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Affiliation(s)
- Bingbing Wan
- a Molecular Biology Program, Memorial Sloan Kettering Cancer Center , New York , NY , USA
| | - Lisa E Hang
- a Molecular Biology Program, Memorial Sloan Kettering Cancer Center , New York , NY , USA
| | - Xiaolan Zhao
- a Molecular Biology Program, Memorial Sloan Kettering Cancer Center , New York , NY , USA
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20
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Abstract
Histone H1 variants, known as linker histones, are essential chromatin components in higher eukaryotes, yet compared to the core histones relatively little is known about their in vivo functions. The filamentous fungus Neurospora crassa encodes a single H1 protein that is not essential for viability. To investigate the role of N. crassa H1, we constructed a functional FLAG-tagged H1 fusion protein and performed genomic and molecular analyses. Cell fractionation experiments showed that H1-3XFLAG is a chromatin binding protein. Chromatin-immunoprecipitation combined with sequencing (ChIP-seq) revealed that H1-3XFLAG is globally enriched throughout the genome with a subtle preference for promoters of expressed genes. In mammals, the stoichiometry of H1 impacts nucleosome repeat length. To determine if H1 impacts nucleosome occupancy or nucleosome positioning in N. crassa, we performed micrococcal nuclease digestion in the wild-type and the ΔhH1 strain followed by sequencing (MNase-seq). Deletion of hH1 did not significantly impact nucleosome positioning or nucleosome occupancy. Analysis of DNA methylation by whole-genome bisulfite sequencing (MethylC-seq) revealed a modest but global increase in DNA methylation in the ΔhH1 mutant. Together, these data suggest that H1 acts as a nonspecific chromatin binding protein that can limit accessibility of the DNA methylation machinery in N. crassa.
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21
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Hang L, Zhao X. The Rtt107 BRCT scaffold and its partner modification enzymes collaborate to promote replication. Nucleus 2016; 7:346-51. [PMID: 27385431 DOI: 10.1080/19491034.2016.1201624] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Faithful duplication of the entire genome during each cell cycle is key for genome maintenance. Each stage of DNA replication, including initiation, progression, and termination, is tightly regulated. Some of these regulations enable replisomes to overcome tens of thousands of template obstacles that block DNA synthesis. Previous studies have identified a large number of proteins that are dedicated to this mission, including protein modification enzymes and scaffold proteins. Protein modification enzymes can bestow fast and reversible changes on many substrates, and thus are ideal for coordinating multiple events needed to promptly overcome replication impediments. Scaffold proteins can support specific protein-protein interactions that enable protein complex formation, protein recruitment, and partner enzyme functions. Taken together with previous studies, our recent work elucidates that a group of modification and scaffold proteins form several complexes to aid replication progression and are particularly important for synthesizing large replicons. Additionally, our work reveals that the intrinsic plasticity of the replication initiation program can be used to compensate for deficient replication progression. (1).
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Affiliation(s)
- Lisa Hang
- a Molecular Biology Program, Memorial Sloan-Kettering Cancer Center , New York , NY , USA
| | - Xiaolan Zhao
- a Molecular Biology Program, Memorial Sloan-Kettering Cancer Center , New York , NY , USA
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22
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Cussiol JR, Dibitetto D, Pellicioli A, Smolka MB. Slx4 scaffolding in homologous recombination and checkpoint control: lessons from yeast. Chromosoma 2016; 126:45-58. [PMID: 27165041 DOI: 10.1007/s00412-016-0600-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 04/27/2016] [Accepted: 04/29/2016] [Indexed: 01/07/2023]
Abstract
Homologous recombination-mediated DNA repair is essential for maintaining genome integrity. It is a multi-step process that involves resection of DNA ends, strand invasion, DNA synthesis and/or DNA end ligation, and finally, the processing of recombination intermediates such as Holliday junctions or other joint molecules. Over the last 15 years, it has been established that the Slx4 protein plays key roles in the processing of recombination intermediates, functioning as a scaffold to coordinate the action of structure-specific endonucleases. Recent work in budding yeast has uncovered unexpected roles for Slx4 in the initial step of DNA-end resection and in the modulation of DNA damage checkpoint signaling. Here we review these latest findings and discuss the emerging role of yeast Slx4 as an important coordinator of DNA damage signaling responses and a regulator of multiple steps in homologous recombination-mediated repair.
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Affiliation(s)
- José R Cussiol
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Diego Dibitetto
- Department of Biosciences, University of Milan, 20133, Milan, Italy
| | | | - Marcus B Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA.
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23
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Rtt107 BRCT domains act as a targeting module in the DNA damage response. DNA Repair (Amst) 2015; 37:22-32. [PMID: 26641499 DOI: 10.1016/j.dnarep.2015.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Revised: 10/22/2015] [Accepted: 10/22/2015] [Indexed: 01/11/2023]
Abstract
Cells are constantly exposed to assaults that cause DNA damage, which must be detected and repaired to prevent genome instability. The DNA damage response is mediated by key kinases that activate various signaling pathways. In Saccharomyces cerevisiae, one of these kinases is Mec1, which phosphorylates numerous targets, including H2A and the DNA damage protein Rtt107. In addition to being phosphorylated, Rtt107 contains six BRCA1 C-terminal (BRCT) domains, which typically recognize phospho-peptides. Thus Rtt107 represented an opportunity to study complementary aspects of the phosphorylation cascades within one protein. Here we sought to describe the functional roles of the multiple BRCT domains in Rtt107. Rtt107 BRCT5/6 facilitated recruitment to sites of DNA lesions via its interaction with phosphorylated H2A. Rtt107 BRCT3/4 also contributed to Rtt107 recruitment, but BRCT3/4 was not sufficient for recruitment when BRCT5/6 was absent. Intriguingly, both mutations that affected Rtt107 recruitment also abrogated its phosphorylation. Pointing to its modular nature, replacing Rtt107 BRCT5/6 with the BRCT domains from the checkpoint protein Rad9 was able to sustain Rtt107 function. Although Rtt107 physically interacts with both the endonuclease Slx4 and the DNA replication and repair protein Dpb11, only Slx4 was dependent on Rtt107 for its recruitment to DNA lesions. Fusing Rtt107 BRCT5/6 to Slx4, which presumably allows artificial recruitment of Slx4 to DNA lesions, alleviated some phenotypes of rtt107Δ mutants, indicating the functional importance of Slx4 recruitment. Together this data revealed a key function of the Rtt107 BRCT domains for targeting of both itself and its interaction partners to DNA lesions.
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24
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Dibitetto D, Ferrari M, Rawal CC, Balint A, Kim T, Zhang Z, Smolka MB, Brown GW, Marini F, Pellicioli A. Slx4 and Rtt107 control checkpoint signalling and DNA resection at double-strand breaks. Nucleic Acids Res 2015; 44:669-82. [PMID: 26490958 PMCID: PMC4737138 DOI: 10.1093/nar/gkv1080] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/06/2015] [Indexed: 11/13/2022] Open
Abstract
The DNA damage checkpoint pathway is activated in response to DNA lesions and replication stress to preserve genome integrity. However, hyper-activation of this surveillance system is detrimental to the cell, because it might prevent cell cycle re-start after repair, which may also lead to senescence. Here we show that the scaffold proteins Slx4 and Rtt107 limit checkpoint signalling at a persistent double-strand DNA break (DSB) and at uncapped telomeres. We found that Slx4 is recruited within a few kilobases of an irreparable DSB, through the interaction with Rtt107 and the multi-BRCT domain scaffold Dpb11. In the absence of Slx4 or Rtt107, Rad9 binding near the irreparable DSB is increased, leading to robust checkpoint signalling and slower nucleolytic degradation of the 5′ strand. Importantly, in slx4Δ sae2Δ double mutant cells these phenotypes are exacerbated, causing a severe Rad9-dependent defect in DSB repair. Our study sheds new light on the molecular mechanism that coordinates the processing and repair of DSBs with DNA damage checkpoint signalling, preserving genome integrity.
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Affiliation(s)
- Diego Dibitetto
- Department of Biosciences, University of Milan, 20133, Milano, Italy
| | - Matteo Ferrari
- Department of Biosciences, University of Milan, 20133, Milano, Italy
| | - Chetan C Rawal
- Department of Biosciences, University of Milan, 20133, Milano, Italy
| | - Attila Balint
- Department of Biochemistry, University of Toronto, Toronto, Ontario, M5S3E1, Canada Donnelly Centre, University of Toronto, Toronto, Ontario, M5S3E1, Canada
| | - TaeHyung Kim
- Donnelly Centre, University of Toronto, Toronto, Ontario, M5S3E1, Canada Department of Computer Science, University of Toronto, Toronto, Ontario, M5S3E1, Canada
| | - Zhaolei Zhang
- Donnelly Centre, University of Toronto, Toronto, Ontario, M5S3E1, Canada Department of Computer Science, University of Toronto, Toronto, Ontario, M5S3E1, Canada
| | - Marcus B Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Grant W Brown
- Department of Biochemistry, University of Toronto, Toronto, Ontario, M5S3E1, Canada Donnelly Centre, University of Toronto, Toronto, Ontario, M5S3E1, Canada
| | - Federica Marini
- Department of Biosciences, University of Milan, 20133, Milano, Italy
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25
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Mejia-Ramirez E, Limbo O, Langerak P, Russell P. Critical Function of γH2A in S-Phase. PLoS Genet 2015; 11:e1005517. [PMID: 26368543 PMCID: PMC4569340 DOI: 10.1371/journal.pgen.1005517] [Citation(s) in RCA: 17] [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: 05/04/2015] [Accepted: 08/20/2015] [Indexed: 11/24/2022] Open
Abstract
Phosphorylation of histone H2AX by ATM and ATR establishes a chromatin recruitment platform for DNA damage response proteins. Phospho-H2AX (γH2AX) has been most intensively studied in the context of DNA double-strand breaks caused by exogenous clastogens, but recent studies suggest that DNA replication stress also triggers formation of γH2A (ortholog of γH2AX) in Schizosaccharomyces pombe. Here, a focused genetic screen in fission yeast reveals that γH2A is critical when there are defects in Replication Factor C (RFC), which loads proliferating cell nuclear antigen (PCNA) clamp onto duplex DNA. Surprisingly Chk1, Cds1/Chk2 and the Rad9-Hus1-Rad1 checkpoint clamp, which are crucial for surviving many genotoxins, are fully dispensable in RFC-defective cells. Immunoblot analysis confirms that Rad9-Hus1-Rad1 is not required for formation of γH2A by Rad3/ATR in S-phase. Defects in DNA polymerase epsilon, which binds PCNA in the replisome, also create an acute need for γH2A. These requirements for γH2A were traced to its role in docking with Brc1, which is a 6-BRCT-domain protein that is structurally related to budding yeast Rtt107 and mammalian PTIP. Brc1, which localizes at stalled replication forks by binding γH2A, prevents aberrant formation of Replication Protein A (RPA) foci in RFC-impaired cells, suggesting that Brc1-coated chromatin stabilizes replisomes when PCNA or DNA polymerase availability limits DNA synthesis. ATM (ataxia telangiectasia mutated) and ATR (ATM and Rad3 related) are evolutionary conserved protein kinases that phosphorylate the carboxyl-tail of histone H2AX in chromatin flanking DNA lesions. Phosphorylated histone H2AX (aka γH2AX) tethers important DNA damage response (DDR) proteins to DNA double-strand breaks but its function during DNA replication is unclear. A novel genetic screen reveals that a partial defect in Replication Factor C (RFC) creates a critical requirement for γH2AX in fission yeast. These studies indicate that γH2AX stabilizes replication forks by recruiting Brc1 when RFC is unable to load the DNA clamp known as proliferating cell nuclear antigen (PCNA) onto duplex DNA. Surprisingly, this activity of γH2AX is more critical than ATM/ATR-mediated activation of the checkpoint kinase Chk1 and Chk2.
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Affiliation(s)
- Eva Mejia-Ramirez
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Oliver Limbo
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Petra Langerak
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Paul Russell
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail:
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26
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Balint A, Kim T, Gallo D, Cussiol JR, Bastos de Oliveira FM, Yimit A, Ou J, Nakato R, Gurevich A, Shirahige K, Smolka MB, Zhang Z, Brown GW. Assembly of Slx4 signaling complexes behind DNA replication forks. EMBO J 2015; 34:2182-97. [PMID: 26113155 DOI: 10.15252/embj.201591190] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 06/02/2015] [Indexed: 12/30/2022] Open
Abstract
Obstructions to replication fork progression, referred to collectively as DNA replication stress, challenge genome stability. In Saccharomyces cerevisiae, cells lacking RTT107 or SLX4 show genome instability and sensitivity to DNA replication stress and are defective in the completion of DNA replication during recovery from replication stress. We demonstrate that Slx4 is recruited to chromatin behind stressed replication forks, in a region that is spatially distinct from that occupied by the replication machinery. Slx4 complex formation is nucleated by Mec1 phosphorylation of histone H2A, which is recognized by the constitutive Slx4 binding partner Rtt107. Slx4 is essential for recruiting the Mec1 activator Dpb11 behind stressed replication forks, and Slx4 complexes are important for full activity of Mec1. We propose that Slx4 complexes promote robust checkpoint signaling by Mec1 by stably recruiting Dpb11 within a discrete domain behind the replication fork, during DNA replication stress.
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Affiliation(s)
- Attila Balint
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - TaeHyung Kim
- Donnelly Centre, University of Toronto, Toronto, ON, Canada Department of Computer Science, University of Toronto, Toronto, ON, Canada
| | - David Gallo
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Jose Renato Cussiol
- Department of Molecular Biology and Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Francisco M Bastos de Oliveira
- Department of Molecular Biology and Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Askar Yimit
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Jiongwen Ou
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Ryuichiro Nakato
- Institute of Molecular and Cellular Biosciences, Research Center for Epigenetic Disease, University of Tokyo, Tokyo, Japan
| | - Alexey Gurevich
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Katsuhiko Shirahige
- Institute of Molecular and Cellular Biosciences, Research Center for Epigenetic Disease, University of Tokyo, Tokyo, Japan
| | - Marcus B Smolka
- Department of Molecular Biology and Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Zhaolei Zhang
- Donnelly Centre, University of Toronto, Toronto, ON, Canada Department of Computer Science, University of Toronto, Toronto, ON, Canada
| | - Grant W Brown
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada Donnelly Centre, University of Toronto, Toronto, ON, Canada
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27
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Cussiol JR, Jablonowski CM, Yimit A, Brown GW, Smolka MB. Dampening DNA damage checkpoint signalling via coordinated BRCT domain interactions. EMBO J 2015; 34:1704-17. [PMID: 25896509 DOI: 10.15252/embj.201490834] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/27/2015] [Indexed: 11/09/2022] Open
Abstract
In response to DNA damage, checkpoint signalling protects genome integrity at the cost of repressing cell cycle progression and DNA replication. Mechanisms for checkpoint down-regulation are therefore necessary for proper cellular proliferation. We recently uncovered a phosphatase-independent mechanism for dampening checkpoint signalling, where the checkpoint adaptor Rad9 is counteracted by the repair scaffolds Slx4-Rtt107. Here, we establish the molecular requirements for this new mode of checkpoint regulation. We engineered a minimal multi-BRCT-domain (MBD) module that recapitulates the action of Slx4-Rtt107 in checkpoint down-regulation. MBD mimics the damage-induced Dpb11-Slx4-Rtt107 complex by synergistically interacting with lesion-specific phospho-sites in Ddc1 and H2A. We propose that efficient recruitment of Dpb11-Slx4-Rtt107 or MBD via a cooperative 'two-site-docking' mechanism displaces Rad9. MBD also interacts with the Mus81 nuclease following checkpoint dampening, suggesting a spatio-temporal coordination of checkpoint signalling and DNA repair via a combinatorial mode of BRCT-domains interactions.
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Affiliation(s)
- José R Cussiol
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Carolyn M Jablonowski
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Askar Yimit
- Donnelly Centre and Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Grant W Brown
- Donnelly Centre and Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Marcus B Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
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28
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Genetic Interaction Landscape Reveals Critical Requirements for Schizosaccharomyces pombe Brc1 in DNA Damage Response Mutants. G3-GENES GENOMES GENETICS 2015; 5:953-62. [PMID: 25795664 PMCID: PMC4426379 DOI: 10.1534/g3.115.017251] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Brc1, which was first identified as a high-copy, allele-specific suppressor of a mutation impairing the Smc5-Smc6 holocomplex in Schizosaccharomyces pombe, protects genome integrity during normal DNA replication and when cells are exposed to toxic compounds that stall or collapse replication forks. The C-terminal tandem BRCT (BRCA1 C-terminus) domain of fission yeast Brc1 docks with phosphorylated histone H2A (γH2A)-marked chromatin formed by ATR/Rad3 checkpoint kinase at arrested and damaged replication forks; however, how Brc1 functions in relation to other genome protection modules remains unclear. Here, an epistatic mini-array profile reveals critical requirements for Brc1 in mutants that are defective in multiple DNA damage response pathways, including checkpoint signaling by Rad3-Rad26/ATR-ATRIP kinase, DNA repair by Smc5-Smc6 holocomplex, replication fork stabilization by Mrc1/claspin and Swi1-Swi3/Timeless-Tipin, and control of ubiquitin-regulated proteolysis by the COP9 signalosome (CSN). Exogenous genotoxins enhance these negative genetic interactions. Rad52 and RPA foci are increased in CSN-defective cells, and loss of γH2A increases genotoxin sensitivity, indicating a critical role for the γH2A-Brc1 module in stabilizing replication forks in CSN-defective cells. A negative genetic interaction with the Nse6 subunit of Smc5-Smc6 holocomplex indicates that the DNA repair functions of Brc1 and Smc5-Smc6 holocomplex are at least partially independent. Rtt107, the Brc1 homolog in Saccharomyces cerevisiae, has a very different pattern of genetic interactions, indicating evolutionary divergence of functions and DNA damage responses.
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29
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Zou Y, Shao Z, Peng J, Li F, Gong D, Wang C, Zuo X, Zhang Z, Wu J, Shi Y, Gong Q. Crystal structure of triple-BRCT-domain of ECT2 and insights into the binding characteristics to CYK-4. FEBS Lett 2014; 588:2911-20. [PMID: 25068414 DOI: 10.1016/j.febslet.2014.07.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 06/29/2014] [Accepted: 07/14/2014] [Indexed: 11/18/2022]
Abstract
Homo sapiens ECT2 is a cell cycle regulator that plays critical roles in cytokinesis. ECT2 activity is restrained during interphase via intra-molecular interactions that involve its N-terminal triple-BRCT-domain and its C-terminal DH-PH domain. At anaphase, this self-inhibitory mechanism is relieved by Plk1-phosphorylated CYK-4, which directly engages the ECT2 BRCT domain. To provide a structural perspective for this auto-inhibitory property, we solved the crystal structure of the ECT2 triple-BRCT-domain. In addition, we systematically analyzed the interaction between the ECT2 BRCT domains with phospho-peptides derived from its binding partner CYK-4, and have identified Ser164 as the major phospho-residue that links CYK-4 to the second ECT2 BRCT domain.
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Affiliation(s)
- Yang Zou
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhenhua Shao
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Junhui Peng
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Fudong Li
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Deshun Gong
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Chongyuan Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiaobing Zuo
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60349, USA
| | - Zhiyong Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jihui Wu
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yunyu Shi
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Qingguo Gong
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
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Heterochromatin controls γH2A localization in Neurospora crassa. EUKARYOTIC CELL 2014; 13:990-1000. [PMID: 24879124 DOI: 10.1128/ec.00117-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In response to genotoxic stress, ATR and ATM kinases phosphorylate H2A in fungi and H2AX in animals on a C-terminal serine. The resulting modified histone, called γH2A, recruits chromatin-binding proteins that stabilize stalled replication forks or promote DNA double-strand-break repair. To identify genomic loci that might be prone to replication fork stalling or DNA breakage in Neurospora crassa, we performed chromatin immunoprecipitation (ChIP) of γH2A followed by next-generation sequencing (ChIP-seq). γH2A-containing nucleosomes are enriched in Neurospora heterochromatin domains. These domains are comprised of A·T-rich repetitive DNA sequences associated with histone H3 methylated at lysine-9 (H3K9me), the H3K9me-binding protein heterochromatin protein 1 (HP1), and DNA cytosine methylation. H3K9 methylation, catalyzed by DIM-5, is required for normal γH2A localization. In contrast, γH2A is not required for H3K9 methylation or DNA methylation. Normal γH2A localization also depends on HP1 and a histone deacetylase, HDA-1, but is independent of the DNA methyltransferase DIM-2. γH2A is globally induced in dim-5 mutants under normal growth conditions, suggesting that the DNA damage response is activated in these mutants in the absence of exogenous DNA damage. Together, these data suggest that heterochromatin formation is essential for normal DNA replication or repair.
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Matthews LA, Selvaratnam R, Jones DR, Akimoto M, McConkey BJ, Melacini G, Duncker BP, Guarné A. A novel non-canonical forkhead-associated (FHA) domain-binding interface mediates the interaction between Rad53 and Dbf4 proteins. J Biol Chem 2013; 289:2589-99. [PMID: 24285546 DOI: 10.1074/jbc.m113.517060] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Forkhead-associated (FHA) and BRCA1 C-terminal (BRCT) domains are overrepresented in DNA damage and replication stress response proteins. They function primarily as phosphoepitope recognition modules but can also mediate non-canonical interactions. The latter are rare, and only a few have been studied at a molecular level. We have identified a crucial non-canonical interaction between the N-terminal FHA1 domain of the checkpoint effector kinase Rad53 and the BRCT domain of the regulatory subunit of the Dbf4-dependent kinase that is critical to suppress late origin firing and to stabilize stalled forks during replication stress. The Rad53-Dbf4 interaction is phosphorylation-independent and involves a novel non-canonical interface on the FHA1 domain. Mutations within this surface result in hypersensitivity to genotoxic stress. Importantly, this surface is not conserved in the FHA2 domain of Rad53, suggesting that the FHA domains of Rad53 gain specificity by engaging additional interaction interfaces beyond their phosphoepitope-binding site. In general, our results point to FHA domains functioning as complex logic gates rather than mere phosphoepitope-targeting modules.
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Abstract
This review focuses on a structure-based analysis of histone posttranslational modification (PTM) readout, where the PTMs serve as docking sites for reader modules as part of larger complexes displaying chromatin modifier and remodeling activities, with the capacity to alter chromatin architecture and templated processes. Individual topics addressed include the diversity of reader-binding pocket architectures and common principles underlying readout of methyl-lysine and methyl-arginine marks, their unmodified counterparts, as well as acetyl-lysine and phosphoserine marks. The review also discusses the impact of multivalent readout of combinations of PTMs localized at specific genomic sites by linked binding modules on processes ranging from gene transcription to repair. Additional topics include cross talk between histone PTMs, histone mimics, epigenetic-based diseases, and drug-based therapeutic intervention. The review ends by highlighting new initiatives and advances, as well as future challenges, toward the promise of enhancing our structural and mechanistic understanding of the readout of histone PTMs at the nucleosomal level.
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Affiliation(s)
- Dinshaw J Patel
- Structural Biology Department, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
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Liu X, Ladias JAA. Structural basis for the BRCA1 BRCT interaction with the proteins ATRIP and BAAT1. Biochemistry 2013; 52:7618-27. [PMID: 24073851 DOI: 10.1021/bi400714v] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The breast and ovarian cancer susceptibility protein 1 (BRCA1) plays a central role in DNA damage response (DDR). Two tandem BRCA1 C-terminal (BRCT) domains interact with several proteins that function in DDR and contain the generally accepted motif pS-X-X-F (pS denoting phosphoserine and X any amino acid), including the ATR-interacting protein (ATRIP) and the BRCA1-associated protein required for ATM activation-1 (BAAT1). The crystal structures of the BRCA1 BRCTs bound to the phosphopeptides ATRIP (235-PEACpSPQFG-243) and BAAT1 (266-VARpSPVFSS-274) were determined at 1.75 Å and 2.2 Å resolution, respectively. The pSer and Phe(+3) anchor the phosphopeptides into the BRCT binding groove, with adjacent peptide residues contributing to the interaction. In the BRCA1-ATRIP structure, Gln(+2) is accommodated through a conformational change of the BRCA1 E1698 side chain. Importantly, isothermal titration calorimetry experiments showed that the size and charge of the side chains at peptide positions +1 and +2 contribute significantly to the BRCA1 BRCT-peptide binding affinity. In particular, the Asp(+1) and Glu(+2) in the human CDC27 peptide 816-HAAEpSDEF-823 abrogate the interaction with the BRCA1 BRCTs due in large part to electrostatic repulsion between Glu(+2) and E1698, indicating a preference of these domains for specific side chains at positions +1 and +2. These results emphasize the need for a systematic assessment of the contribution of the peptide residues surrounding pSer and Phe(+3) to the binding affinity and specificity of the BRCA1 BRCTs in order to elucidate the molecular mechanisms underlying the hierarchy of target selection by these versatile domains during DDR and tumorigenesis.
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Affiliation(s)
- Xuying Liu
- Molecular Medicine Laboratory and Macromolecular Crystallography Unit, Department of Medicine, Harvard Medical School , Boston Massachusetts 02215, United States
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Garg J, Lambert JP, Karsou A, Marquez S, Nabeel-Shah S, Bertucci V, Retnasothie DV, Radovani E, Pawson T, Gingras AC, Pearlman RE, Fillingham JS. Conserved Asf1-importin β physical interaction in growth and sexual development in the ciliate Tetrahymena thermophila. J Proteomics 2013; 94:311-26. [PMID: 24120531 DOI: 10.1016/j.jprot.2013.09.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 09/07/2013] [Accepted: 09/23/2013] [Indexed: 01/14/2023]
Abstract
UNLABELLED How the eukaryotic cell specifies distinct chromatin domains is a central problem in molecular biology. The ciliate protozoan Tetrahymena thermophila features a separation of structurally and functionally distinct germ-line and somatic chromatin into two distinct nuclei, the micronucleus (MIC) and macronucleus (MAC) respectively. To address questions about how distinct chromatin states are assembled in the MAC and MIC, we have initiated studies to define protein-protein interactions for T. thermophila chromatin-related proteins. Affinity purification followed by mass spectrometry analysis of the conserved Asf1 histone chaperone in T. thermophila revealed that it forms a complex with an importin β, ImpB6. Furthermore, these proteins co-localized to both the MAC and MIC in growth and development. We suggest that newly synthesized histones H3 and H4 in T. thermophila are transported via Asf1-ImpB6 in an evolutionarily conserved pathway to both nuclei where they then enter nucleus-specific chromatin assembly pathways. These studies set the stage for further use of functional proteomics to elucidate details of the characterization and functional analysis of the unique chromatin domains in T. thermophila. BIOLOGICAL SIGNIFICANCE Asf1 is an evolutionarily conserved chaperone of H3 and H4 histones that functions in replication dependent and independent chromatin assembly. Although Asf1 has been well studied in humans and yeast (members of the Opisthokonta lineage of eukaryotes), questions remain concerning its mechanism of function. To obtain additional insight into the Asf1 function we have initiated a proteomic analysis in the ciliate protozoan T. thermophila, a member of the Alveolata lineage of eukaryotes. Our results suggest that an evolutionarily conserved function of Asf1 is mediating the nuclear transport of newly synthesized histones H3 and H4.
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Affiliation(s)
- Jyoti Garg
- Department of Biology, York University, 4700 Keele St., Toronto M3J 1P3, Canada
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Replication checkpoint: tuning and coordination of replication forks in s phase. Genes (Basel) 2013; 4:388-434. [PMID: 24705211 PMCID: PMC3924824 DOI: 10.3390/genes4030388] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 07/30/2013] [Accepted: 08/02/2013] [Indexed: 12/01/2022] Open
Abstract
Checkpoints monitor critical cell cycle events such as chromosome duplication and segregation. They are highly conserved mechanisms that prevent progression into the next phase of the cell cycle when cells are unable to accomplish the previous event properly. During S phase, cells also provide a surveillance mechanism called the DNA replication checkpoint, which consists of a conserved kinase cascade that is provoked by insults that block or slow down replication forks. The DNA replication checkpoint is crucial for maintaining genome stability, because replication forks become vulnerable to collapse when they encounter obstacles such as nucleotide adducts, nicks, RNA-DNA hybrids, or stable protein-DNA complexes. These can be exogenously induced or can arise from endogenous cellular activity. Here, we summarize the initiation and transduction of the replication checkpoint as well as its targets, which coordinate cell cycle events and DNA replication fork stability.
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Lee SY, Russell P. Brc1 links replication stress response and centromere function. Cell Cycle 2013; 12:1665-71. [PMID: 23656778 DOI: 10.4161/cc.24900] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Protection of genome integrity depends on the coordinated activities of DNA replication, DNA repair, chromatin assembly and chromosome segregation mechanisms. DNA lesions are detected by the master checkpoint kinases ATM (Tel1) and ATR (Rad3/Mec1), which phosphorylate multiple substrates, including a C-terminal SQ motif in histone H2A or H2AX. The 6-BRCT domain protein Brc1, which is required for efficient recovery from replication fork arrest and collapse in fission yeast, binds phospho-histone H2A (γH2A)-coated chromatin at stalled and damaged replication forks. We recently found that Brc1 co-localizes with γH2A that appears in pericentromeric heterochromatin during S-phase. Our studies indicate that Brc1 contributes to the maintenance of pericentromeric heterochromatin, which is required for efficient chromosome segregation during mitosis. Here, we review these studies and present additional results that establish the functional requirements for the N-terminal BRCT domains of Brc1 in the replication stress response and resistance to the microtubule destabilizing drug thiabendazole (TBZ). We also identify the nuclear localization signal (NLS) in Brc1, which closely abuts the C-terminal pair of BRCT domains that form the γH2A-binding pocket. This compact arrangement of localization domains may be a shared feature of other γH2A-binding proteins, including Rtt107, PTIP and Mdc1.
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Affiliation(s)
- Si Young Lee
- Cell and Molecular Biology Department, The Scripps Research Institute, La Jolla, CA USA
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37
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Perceiving the epigenetic landscape through histone readers. Nat Struct Mol Biol 2013; 19:1218-27. [PMID: 23211769 DOI: 10.1038/nsmb.2436] [Citation(s) in RCA: 579] [Impact Index Per Article: 52.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 10/01/2012] [Indexed: 12/24/2022]
Abstract
Post-translational modifications (PTMs) of histones provide a fine-tuned mechanism for regulating chromatin structure and dynamics. PTMs can alter direct interactions between histones and DNA and serve as docking sites for protein effectors, or readers, of these PTMs. Binding of the readers recruits or stabilizes various components of the nuclear signaling machinery at specific genomic sites, mediating fundamental DNA-templated processes, including gene transcription and DNA recombination, replication and repair. In this review, we highlight the latest advances in characterizing histone-binding mechanisms and identifying new epigenetic readers and summarize the functional significance of PTM recognition.
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Abstract
The coordinated replication and transcription of pericentromeric repeats enable RNA interference (RNAi)-mediated transmission of pericentromeric heterochromatin in fission yeast, which is essential for the proper function of centromeres. Rad3/ATR kinase phosphorylates histone H2A on serine-128/-129 to create γH2A in pericentromeric heterochromatin during S phase, which recruits Brc1 through its breast cancer gene 1 protein (BRCA1) C-terminal (BRCT) domains. Brc1 prevents the collapse of stalled replication forks; however, it is unknown whether this activity influences centromere function. Here, we show that Brc1 localizes in pericentromeric heterochromatin during S phase, where it enhances Clr4/Suv39-mediated H3 lysine-9 dimethylation (H3K9me2) and gene silencing. Loss of Brc1 increases sensitivity to the microtubule-destabilizing drug thiabendazole (TBZ) and increases chromosome missegregation in the presence of TBZ. Brc1 retains significant function even when it cannot bind γH2A. However, elimination of the serine-121 site on histone H2A, a target of Bub1 spindle assembly checkpoint kinase, sensitizes γH2A-deficient and brc1Δ cells to replication stress and microtubule destabilization. Collective results suggest that Brc1-mediated stabilization of stalled replication forks is necessary for fully efficient transmission of pericentromeric heterochromatin, which is required for accurate chromosome segregation during mitosis.
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DNA-repair scaffolds dampen checkpoint signalling by counteracting the adaptor Rad9. Nature 2012; 493:120-4. [PMID: 23160493 PMCID: PMC3536934 DOI: 10.1038/nature11658] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 10/04/2012] [Indexed: 01/20/2023]
Abstract
In response to genotoxic stress, a transient arrest in cell-cycle progression enforced by the DNA-damage checkpoint (DDC) signalling pathway positively contributes to genome maintenance. Because hyperactivated DDC signalling can lead to a persistent and detrimental cell-cycle arrest, cells must tightly regulate the activity of the kinases involved in this pathway. Despite their importance, the mechanisms for monitoring and modulating DDC signalling are not fully understood. Here we show that the DNA-repair scaffolding proteins Slx4 and Rtt107 prevent the aberrant hyperactivation of DDC signalling by lesions that are generated during DNA replication in Saccharomyces cerevisiae. On replication stress, cells lacking Slx4 or Rtt107 show hyperactivation of the downstream DDC kinase Rad53, whereas activation of the upstream DDC kinase Mec1 remains normal. An Slx4-Rtt107 complex counteracts the checkpoint adaptor Rad9 by physically interacting with Dpb11 and phosphorylated histone H2A, two positive regulators of Rad9-dependent Rad53 activation. A decrease in DDC signalling results from hypomorphic mutations in RAD53 and H2A and rescues the hypersensitivity to replication stress of cells lacking Slx4 or Rtt107. We propose that the Slx4-Rtt107 complex modulates Rad53 activation by a competition-based mechanism that balances the engagement of Rad9 at replication-induced lesions. Our findings show that DDC signalling is monitored and modulated through the direct action of DNA-repair factors.
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Replication fork collapse and genome instability in a deoxycytidylate deaminase mutant. Mol Cell Biol 2012; 32:4445-54. [PMID: 22927644 DOI: 10.1128/mcb.01062-12] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ribonucleotide reductase (RNR) and deoxycytidylate deaminase (dCMP deaminase) are pivotal allosteric enzymes required to maintain adequate pools of deoxyribonucleoside triphosphates (dNTPs) for DNA synthesis and repair. Whereas RNR inhibition slows DNA replication and activates checkpoint responses, the effect of dCMP deaminase deficiency is largely unknown. Here, we report that deleting the Schizosaccharomyces pombe dcd1(+) dCMP deaminase gene (SPBC2G2.13c) increases dCTP ∼30-fold and decreases dTTP ∼4-fold. In contrast to the robust growth of a Saccharomyces cerevisiae dcd1Δ mutant, fission yeast dcd1Δ cells delay cell cycle progression in early S phase and are sensitive to multiple DNA-damaging agents, indicating impaired DNA replication and repair. DNA content profiling of dcd1Δ cells differs from an RNR-deficient mutant. Dcd1 deficiency activates genome integrity checkpoints enforced by Rad3 (ATR), Cds1 (Chk2), and Chk1 and creates critical requirements for proteins involved in recovery from replication fork collapse, including the γH2AX-binding protein Brc1 and Mus81 Holliday junction resolvase. These effects correlate with increased nuclear foci of the single-stranded DNA binding protein RPA and the homologous recombination repair protein Rad52. Moreover, Brc1 suppresses spontaneous mutagenesis in dcd1Δ cells. We propose that replication forks stall and collapse in dcd1Δ cells, burdening DNA damage and checkpoint responses to maintain genome integrity.
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