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Hays M. Genetic conflicts in budding yeast: The 2μ plasmid as a model selfish element. Semin Cell Dev Biol 2024; 161-162:31-41. [PMID: 38598944 DOI: 10.1016/j.semcdb.2024.04.002] [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: 09/26/2023] [Revised: 04/02/2024] [Accepted: 04/04/2024] [Indexed: 04/12/2024]
Abstract
Antagonistic coevolution, arising from genetic conflict, can drive rapid evolution and biological innovation. Conflict can arise both between organisms and within genomes. This review focuses on budding yeasts as a model system for exploring intra- and inter-genomic genetic conflict, highlighting in particular the 2-micron (2μ) plasmid as a model selfish element. The 2μ is found widely in laboratory strains and industrial isolates of Saccharomyces cerevisiae and has long been known to cause host fitness defects. Nevertheless, the plasmid is frequently ignored in the context of genetic, fitness, and evolution studies. Here, I make a case for further exploring the evolutionary impact of the 2μ plasmid as well as other selfish elements of budding yeasts, discuss recent advances, and, finally, future directions for the field.
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Affiliation(s)
- Michelle Hays
- Department of Genetics, Stanford University, Stanford, CA, United States.
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2
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Roy S, Adhikary H, D’Amours D. The SMC5/6 complex: folding chromosomes back into shape when genomes take a break. Nucleic Acids Res 2024; 52:2112-2129. [PMID: 38375830 PMCID: PMC10954462 DOI: 10.1093/nar/gkae103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/28/2024] [Accepted: 02/01/2024] [Indexed: 02/21/2024] Open
Abstract
High-level folding of chromatin is a key determinant of the shape and functional state of chromosomes. During cell division, structural maintenance of chromosome (SMC) complexes such as condensin and cohesin ensure large-scale folding of chromatin into visible chromosomes. In contrast, the SMC5/6 complex plays more local and context-specific roles in the structural organization of interphase chromosomes with important implications for health and disease. Recent advances in single-molecule biophysics and cryo-electron microscopy revealed key insights into the architecture of the SMC5/6 complex and how interactions connecting the complex to chromatin components give rise to its unique repertoire of interphase functions. In this review, we provide an integrative view of the features that differentiates the SMC5/6 complex from other SMC enzymes and how these enable dramatic reorganization of DNA folding in space during DNA repair reactions and other genome transactions. Finally, we explore the mechanistic basis for the dynamic targeting of the SMC5/6 complex to damaged chromatin and its crucial role in human health.
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Affiliation(s)
- Shamayita Roy
- Ottawa Institute of Systems Biology, Department of Cellular and Molecular Medicine, University of Ottawa, Roger Guindon Hall, 451 Smyth Rd, Ottawa, ON K1H 8M5, Canada
| | - Hemanta Adhikary
- Ottawa Institute of Systems Biology, Department of Cellular and Molecular Medicine, University of Ottawa, Roger Guindon Hall, 451 Smyth Rd, Ottawa, ON K1H 8M5, Canada
| | - Damien D’Amours
- Ottawa Institute of Systems Biology, Department of Cellular and Molecular Medicine, University of Ottawa, Roger Guindon Hall, 451 Smyth Rd, Ottawa, ON K1H 8M5, Canada
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3
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Mahrik L, Stefanovie B, Maresova A, Princova J, Kolesar P, Lelkes E, Faux C, Helmlinger D, Prevorovsky M, Palecek JJ. The SAGA histone acetyltransferase module targets SMC5/6 to specific genes. Epigenetics Chromatin 2023; 16:6. [PMID: 36793083 PMCID: PMC9933293 DOI: 10.1186/s13072-023-00480-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 02/02/2023] [Indexed: 02/17/2023] Open
Abstract
BACKGROUND Structural Maintenance of Chromosomes (SMC) complexes are molecular machines driving chromatin organization at higher levels. In eukaryotes, three SMC complexes (cohesin, condensin and SMC5/6) play key roles in cohesion, condensation, replication, transcription and DNA repair. Their physical binding to DNA requires accessible chromatin. RESULTS We performed a genetic screen in fission yeast to identify novel factors required for SMC5/6 binding to DNA. We identified 79 genes of which histone acetyltransferases (HATs) were the most represented. Genetic and phenotypic analyses suggested a particularly strong functional relationship between the SMC5/6 and SAGA complexes. Furthermore, several SMC5/6 subunits physically interacted with SAGA HAT module components Gcn5 and Ada2. As Gcn5-dependent acetylation facilitates the accessibility of chromatin to DNA-repair proteins, we first analysed the formation of DNA-damage-induced SMC5/6 foci in the Δgcn5 mutant. The SMC5/6 foci formed normally in Δgcn5, suggesting SAGA-independent SMC5/6 localization to DNA-damaged sites. Next, we used Nse4-FLAG chromatin-immunoprecipitation (ChIP-seq) analysis in unchallenged cells to assess SMC5/6 distribution. A significant portion of SMC5/6 accumulated within gene regions in wild-type cells, which was reduced in Δgcn5 and Δada2 mutants. The drop in SMC5/6 levels was also observed in gcn5-E191Q acetyltransferase-dead mutant. CONCLUSION Our data show genetic and physical interactions between SMC5/6 and SAGA complexes. The ChIP-seq analysis suggests that SAGA HAT module targets SMC5/6 to specific gene regions and facilitates their accessibility for SMC5/6 loading.
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Affiliation(s)
- L Mahrik
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, 61137, Brno, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - B Stefanovie
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, 61137, Brno, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - A Maresova
- Department of Cell Biology, Faculty of Science, Charles University, Vinicna 7, 12800, Prague, Czech Republic
| | - J Princova
- Department of Cell Biology, Faculty of Science, Charles University, Vinicna 7, 12800, Prague, Czech Republic
| | - P Kolesar
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, 61137, Brno, Czech Republic
| | - E Lelkes
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, 61137, Brno, Czech Republic
| | - C Faux
- Centre de Recherche en Biologie Cellulaire de Montpellier, University of Montpellier, CNRS, 1919 Route de Mende, 34293, Montpellier Cedex 05, France
| | - D Helmlinger
- Centre de Recherche en Biologie Cellulaire de Montpellier, University of Montpellier, CNRS, 1919 Route de Mende, 34293, Montpellier Cedex 05, France
| | - M Prevorovsky
- Department of Cell Biology, Faculty of Science, Charles University, Vinicna 7, 12800, Prague, Czech Republic.
| | - J J Palecek
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, 61137, Brno, Czech Republic.
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic.
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic.
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4
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Smc5/6, an atypical SMC complex with two RING-type subunits. Biochem Soc Trans 2021; 48:2159-2171. [PMID: 32964921 DOI: 10.1042/bst20200389] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 08/26/2020] [Accepted: 08/27/2020] [Indexed: 01/06/2023]
Abstract
The Smc5/6 complex plays essential roles in chromosome segregation and repair, by promoting disjunction of sister chromatids. The core of the complex is constituted by an heterodimer of Structural Maintenance of Chromosomes (SMC) proteins that use ATP hydrolysis to dynamically associate with and organize chromosomes. In addition, the Smc5/6 complex contains six non-SMC subunits. Remarkably, and differently to other SMC complexes, the Nse1 and Nse2 subunits contain RING-type domains typically found in E3 ligases, pointing to the capacity to regulate other proteins and complexes through ubiquitin-like modifiers. Nse2 codes for a C-terminal SP-RING domain with SUMO ligase activity, assisting Smc5/6 functions in chromosome segregation through sumoylation of several chromosome-associated proteins. Nse1 codes for a C-terminal NH-RING domain and, although it has been proposed to have ubiquitin ligase activity, no Smc5/6-dependent ubiquitylation target has been described to date. Here, we review the function of the two RING domains of the Smc5/6 complex in the broader context of SMC complexes as global chromosome organizers of the genome.
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5
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Zou W, Li G, Jian L, Qian J, Liu Y, Zhao J. Arabidopsis SMC6A and SMC6B have redundant function in seed and gametophyte development. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:4871-4887. [PMID: 33909904 DOI: 10.1093/jxb/erab181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 04/25/2021] [Indexed: 05/21/2023]
Abstract
Reproductive development is a crucial process during plant growth. The structural maintenance of chromosome (SMC) 5/6 complex has been studied in various species. However, there are few studies on the biological function of SMC6 in plant development, especially during reproduction. In this study, knocking out of both AtSMC6A and AtSMC6B led to severe defects in Arabidopsis seed development, and expression of AtSMC6A or AtSMC6B could completely restore seed abortion in the smc6a-/-smc6b-/-double mutant. Knocking down AtSMC6A in the smc6b-/- mutant led to defects in female and male development and decreased fertility. The double mutation also resulted in loss of cell viability, and caused embryo and endosperm cell death through vacuolar cell death and necrosis. Furthermore, the expression of genes involved in embryo patterning, endosperm cellularisation, DNA damage repair, cell cycle regulation, and DNA replication were significantly changed in the albino seeds of the double mutant. Moreover, we found that the SMC5/6 complex may participate in the SOG1 (SUPPRESSOR OF GAMMA RESPONSE1)-dependent DNA damage repair pathway. These findings suggest that both AtSMC6A and AtSMC6B are functionally redundant and play important roles in seed and gametophyte development through maintaining chromosome stability in Arabidopsis.
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Affiliation(s)
- Wenxuan Zou
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Gang Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Liufang Jian
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jie Qian
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Yantong Liu
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jie Zhao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
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6
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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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Etheridge TJ, Villahermosa D, Campillo-Funollet E, Herbert AD, Irmisch A, Watson AT, Dang HQ, Osborne MA, Oliver AW, Carr AM, Murray JM. Live-cell single-molecule tracking highlights requirements for stable Smc5/6 chromatin association in vivo. eLife 2021; 10:e68579. [PMID: 33860765 PMCID: PMC8075580 DOI: 10.7554/elife.68579] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 04/15/2021] [Indexed: 12/17/2022] Open
Abstract
The essential Smc5/6 complex is required in response to replication stress and is best known for ensuring the fidelity of homologous recombination. Using single-molecule tracking in live fission yeast to investigate Smc5/6 chromatin association, we show that Smc5/6 is chromatin associated in unchallenged cells and this depends on the non-SMC protein Nse6. We define a minimum of two Nse6-dependent sub-pathways, one of which requires the BRCT-domain protein Brc1. Using defined mutants in genes encoding the core Smc5/6 complex subunits, we show that the Nse3 double-stranded DNA binding activity and the arginine fingers of the two Smc5/6 ATPase binding sites are critical for chromatin association. Interestingly, disrupting the single-stranded DNA (ssDNA) binding activity at the hinge region does not prevent chromatin association but leads to elevated levels of gross chromosomal rearrangements during replication restart. This is consistent with a downstream function for ssDNA binding in regulating homologous recombination.
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Affiliation(s)
- Thomas J Etheridge
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Desiree Villahermosa
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Eduard Campillo-Funollet
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Alex David Herbert
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Anja Irmisch
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Adam T Watson
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Hung Q Dang
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Mark A Osborne
- Chemistry Department, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Antony W Oliver
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Antony M Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Johanne M Murray
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
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8
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Chromatin modifiers and recombination factors promote a telomere fold-back structure, that is lost during replicative senescence. PLoS Genet 2020; 16:e1008603. [PMID: 33370275 PMCID: PMC7793543 DOI: 10.1371/journal.pgen.1008603] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 01/08/2021] [Accepted: 11/03/2020] [Indexed: 12/27/2022] Open
Abstract
Telomeres have the ability to adopt a lariat conformation and hence, engage in long and short distance intra-chromosome interactions. Budding yeast telomeres were proposed to fold back into subtelomeric regions, but a robust assay to quantitatively characterize this structure has been lacking. Therefore, it is not well understood how the interactions between telomeres and non-telomeric regions are established and regulated. We employ a telomere chromosome conformation capture (Telo-3C) approach to directly analyze telomere folding and its maintenance in S. cerevisiae. We identify the histone modifiers Sir2, Sin3 and Set2 as critical regulators for telomere folding, which suggests that a distinct telomeric chromatin environment is a major requirement for the folding of yeast telomeres. We demonstrate that telomeres are not folded when cells enter replicative senescence, which occurs independently of short telomere length. Indeed, Sir2, Sin3 and Set2 protein levels are decreased during senescence and their absence may thereby prevent telomere folding. Additionally, we show that the homologous recombination machinery, including the Rad51 and Rad52 proteins, as well as the checkpoint component Rad53 are essential for establishing the telomere fold-back structure. This study outlines a method to interrogate telomere-subtelomere interactions at a single unmodified yeast telomere. Using this method, we provide insights into how the spatial arrangement of the chromosome end structure is established and demonstrate that telomere folding is compromised throughout replicative senescence.
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9
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Atkins A, Xu MJ, Li M, Rogers NP, Pryzhkova MV, Jordan PW. SMC5/6 is required for replication fork stability and faithful chromosome segregation during neurogenesis. eLife 2020; 9:e61171. [PMID: 33200984 PMCID: PMC7723410 DOI: 10.7554/elife.61171] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 11/16/2020] [Indexed: 12/21/2022] Open
Abstract
Mutations of SMC5/6 components cause developmental defects, including primary microcephaly. To model neurodevelopmental defects, we engineered a mouse wherein Smc5 is conditionally knocked out (cKO) in the developing neocortex. Smc5 cKO mice exhibited neurodevelopmental defects due to neural progenitor cell (NPC) apoptosis, which led to reduction in cortical layer neurons. Smc5 cKO NPCs formed DNA bridges during mitosis and underwent chromosome missegregation. SMC5/6 depletion triggers a CHEK2-p53 DNA damage response, as concomitant deletion of the Trp53 tumor suppressor or Chek2 DNA damage checkpoint kinase rescued Smc5 cKO neurodevelopmental defects. Further assessment using Smc5 cKO and auxin-inducible degron systems demonstrated that absence of SMC5/6 leads to DNA replication stress at late-replicating regions such as pericentromeric heterochromatin. In summary, SMC5/6 is important for completion of DNA replication prior to entering mitosis, which ensures accurate chromosome segregation. Thus, SMC5/6 functions are critical in highly proliferative stem cells during organism development.
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Affiliation(s)
- Alisa Atkins
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Michelle J Xu
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Maggie Li
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Nathaniel P Rogers
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Marina V Pryzhkova
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Philip W Jordan
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
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10
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Abstract
Smc5 and Smc6, together with the kleisin Nse4, form the heart of the enigmatic and poorly understood Smc5/6 complex, which is frequently viewed as a cousin of cohesin and condensin with functions in DNA repair. As novel functions for cohesin and condensin complexes in the organization of long-range chromatin architecture have recently emerged, new unsuspected roles for Smc5/6 have also surfaced. Here, I aim to provide a comprehensive overview of our current knowledge of the Smc5/6 complex, including its long-established function in genome stability, its multiple roles in DNA repair, and its recently discovered connection to the transcription inhibition of hepatitis B virus genomes. In addition, I summarize new research that is beginning to tease out the molecular details of Smc5/6 structure and function, knowledge that will illuminate the nuclear activities of Smc5/6 in the stability and dynamics of eukaryotic genomes.
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Affiliation(s)
- Luis Aragón
- Cell Cycle Group, MRC London Institute of Medical Sciences, Hammersmith Hospital Campus, London W12 0NN, United Kingdom;
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11
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Nakagawa T, Okita AK. Transcriptional silencing of centromere repeats by heterochromatin safeguards chromosome integrity. Curr Genet 2019; 65:1089-1098. [PMID: 30997531 DOI: 10.1007/s00294-019-00975-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 04/11/2019] [Accepted: 04/13/2019] [Indexed: 12/25/2022]
Abstract
The centromere region of chromosomes consists of repetitive DNA sequences, and is, therefore, one of the fragile sites of chromosomes in many eukaryotes. In the core region, the histone H3 variant CENP-A forms centromere-specific nucleosomes that are required for kinetochore formation. In the pericentromeric region, histone H3 is methylated at lysine 9 (H3K9) and heterochromatin is formed. The transcription of pericentromeric repeats by RNA polymerase II is strictly repressed by heterochromatin. However, the role of the transcriptional silencing of the pericentromeric repeats remains largely unclear. Here, we focus on the chromosomal rearrangements that occur at the repetitive centromeres, and highlight our recent studies showing that transcriptional silencing by heterochromatin suppresses gross chromosomal rearrangements (GCRs) at centromeres in fission yeast. Inactivation of the Clr4 methyltransferase, which is essential for the H3K9 methylation, increased GCRs with breakpoints located in centromeric repeats. However, mutations in RNA polymerase II or the transcription factor Tfs1/TFIIS, which promotes restart of RNA polymerase II following its backtracking, reduced the GCRs that occur in the absence of Clr4, demonstrating that heterochromatin suppresses GCRs by repressing the Tfs1-dependent transcription. We also discuss how the transcriptional restart gives rise to chromosomal rearrangements at centromeres.
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Affiliation(s)
- Takuro Nakagawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.
| | - Akiko K Okita
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
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12
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Okita AK, Zafar F, Su J, Weerasekara D, Kajitani T, Takahashi TS, Kimura H, Murakami Y, Masukata H, Nakagawa T. Heterochromatin suppresses gross chromosomal rearrangements at centromeres by repressing Tfs1/TFIIS-dependent transcription. Commun Biol 2019; 2:17. [PMID: 30652128 PMCID: PMC6329695 DOI: 10.1038/s42003-018-0251-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 12/05/2018] [Indexed: 12/20/2022] Open
Abstract
Heterochromatin, characterized by histone H3 lysine 9 (H3K9) methylation, assembles on repetitive regions including centromeres. Although centromeric heterochromatin is important for correct segregation of chromosomes, its exact role in maintaining centromere integrity remains elusive. Here, we found in fission yeast that heterochromatin suppresses gross chromosomal rearrangements (GCRs) at centromeres. Mutations in Clr4/Suv39 methyltransferase increased the formation of isochromosomes, whose breakpoints were located in centromere repeats. H3K9A and H3K9R mutations also increased GCRs, suggesting that Clr4 suppresses centromeric GCRs via H3K9 methylation. HP1 homologs Swi6 and Chp2 and the RNAi component Chp1 were the chromodomain proteins essential for full suppression of GCRs. Remarkably, mutations in RNA polymerase II (RNAPII) or Tfs1/TFIIS, the transcription factor that facilitates restart of RNAPII after backtracking, specifically bypassed the requirement of Clr4 for suppressing GCRs. These results demonstrate that heterochromatin suppresses GCRs by repressing Tfs1-dependent transcription of centromere repeats.
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Affiliation(s)
- Akiko K. Okita
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043 Japan
| | - Faria Zafar
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043 Japan
| | - Jie Su
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043 Japan
| | - Dayalini Weerasekara
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043 Japan
| | - Takuya Kajitani
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810 Japan
- Present Address: Department of Molecular Biology and Genetics, Cornell University, 526 Campus Road, Ithaca, NY 14853 USA
| | - Tatsuro S. Takahashi
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043 Japan
- Present Address: Department of Biology, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395 Japan
| | - Hiroshi Kimura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8503 Japan
| | - Yota Murakami
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810 Japan
| | - Hisao Masukata
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043 Japan
| | - Takuro Nakagawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043 Japan
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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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Palecek JJ. SMC5/6: Multifunctional Player in Replication. Genes (Basel) 2018; 10:genes10010007. [PMID: 30583551 PMCID: PMC6356406 DOI: 10.3390/genes10010007] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 12/18/2018] [Accepted: 12/19/2018] [Indexed: 12/13/2022] Open
Abstract
The genome replication process is challenged at many levels. Replication must proceed through different problematic sites and obstacles, some of which can pause or even reverse the replication fork (RF). In addition, replication of DNA within chromosomes must deal with their topological constraints and spatial organization. One of the most important factors organizing DNA into higher-order structures are Structural Maintenance of Chromosome (SMC) complexes. In prokaryotes, SMC complexes ensure proper chromosomal partitioning during replication. In eukaryotes, cohesin and SMC5/6 complexes assist in replication. Interestingly, the SMC5/6 complexes seem to be involved in replication in many ways. They stabilize stalled RFs, restrain RF regression, participate in the restart of collapsed RFs, and buffer topological constraints during RF progression. In this (mini) review, I present an overview of these replication-related functions of SMC5/6.
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Affiliation(s)
- Jan J Palecek
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, 61137 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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16
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Varejão N, Ibars E, Lascorz J, Colomina N, Torres-Rosell J, Reverter D. DNA activates the Nse2/Mms21 SUMO E3 ligase in the Smc5/6 complex. EMBO J 2018; 37:embj.201798306. [PMID: 29769404 DOI: 10.15252/embj.201798306] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 04/11/2018] [Accepted: 04/20/2018] [Indexed: 11/09/2022] Open
Abstract
Modification of chromosomal proteins by conjugation to SUMO is a key step to cope with DNA damage and to maintain the integrity of the genome. The recruitment of SUMO E3 ligases to chromatin may represent one layer of control on protein sumoylation. However, we currently do not understand how cells upregulate the activity of E3 ligases on chromatin. Here we show that the Nse2 SUMO E3 in the Smc5/6 complex, a critical player during recombinational DNA repair, is directly stimulated by binding to DNA Activation of sumoylation requires the electrostatic interaction between DNA and a positively charged patch in the ARM domain of Smc5, which acts as a DNA sensor that subsequently promotes a stimulatory activation of the E3 activity in Nse2. Specific disruption of the interaction between the ARM of Smc5 and DNA sensitizes cells to DNA damage, indicating that this mechanism contributes to DNA repair. These results reveal a mechanism to enhance a SUMO E3 ligase activity by direct DNA binding and to restrict sumoylation in the vicinity of those Smc5/6-Nse2 molecules engaged on DNA.
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Affiliation(s)
- Nathalia Varejão
- Institut de Biotecnologia i de Biomedicina (IBB), Department of de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Eva Ibars
- Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Department of Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - Jara Lascorz
- Institut de Biotecnologia i de Biomedicina (IBB), Department of de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Neus Colomina
- Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Department of Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - Jordi Torres-Rosell
- Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), Department of Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - David Reverter
- Institut de Biotecnologia i de Biomedicina (IBB), Department of de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
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17
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DNA replication stress and its impact on chromosome segregation and tumorigenesis. Semin Cancer Biol 2018; 55:61-69. [PMID: 29692334 DOI: 10.1016/j.semcancer.2018.04.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 04/13/2018] [Accepted: 04/16/2018] [Indexed: 01/11/2023]
Abstract
Genome instability and cell cycle dysregulation are commonly associated with cancer. DNA replication stress driven by oncogene activation during tumorigenesis is now well established as a source of genome instability. Replication stress generates DNA damage not only during S phase, but also in the subsequent mitosis, where it impacts adversely on chromosome segregation. Some regions of the genome seem particularly sensitive to replication stress-induced instability; most notably, chromosome fragile sites. In this article, we review some of the important issues that have emerged in recent years concerning DNA replication stress and fragile site expression, as well as how chromosome instability is minimized by a family of ring-shaped protein complexes known as SMC proteins. Understanding how replication stress impacts on S phase and mitosis in cancer should provide opportunities for the development of novel and tumour-specific treatments.
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18
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Zilio N, Eifler-Olivi K, Ulrich HD. Functions of SUMO in the Maintenance of Genome Stability. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 963:51-87. [PMID: 28197906 DOI: 10.1007/978-3-319-50044-7_4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Like in most other areas of cellular metabolism, the functions of the ubiquitin-like modifier SUMO in the maintenance of genome stability are manifold and varied. Perturbations of global sumoylation causes a wide spectrum of phenotypes associated with defects in DNA maintenance, such as hypersensitivity to DNA-damaging agents, gross chromosomal rearrangements and loss of entire chromosomes. Consistent with these observations, many key factors involved in various DNA repair pathways have been identified as SUMO substrates. However, establishing a functional connection between a given SUMO target, the cognate SUMO ligase and a relevant phenotype has remained a challenge, mainly because of the difficulties involved in identifying important modification sites and downstream effectors that specifically recognize the target in its sumoylated state. This review will give an overview over the major pathways of DNA repair and genome maintenance influenced by the SUMO system and discuss selected examples of SUMO's actions in these pathways where the biological consequences of the modification have been elucidated.
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Affiliation(s)
- Nicola Zilio
- Institute of Molecular Biology (IMB), Ackermannweg 4, D-55128, Mainz, Germany
| | | | - Helle D Ulrich
- Institute of Molecular Biology (IMB), Ackermannweg 4, D-55128, Mainz, Germany.
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19
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Jalal D, Chalissery J, Hassan AH. Genome maintenance in Saccharomyces cerevisiae: the role of SUMO and SUMO-targeted ubiquitin ligases. Nucleic Acids Res 2017; 45:2242-2261. [PMID: 28115630 PMCID: PMC5389695 DOI: 10.1093/nar/gkw1369] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 01/02/2017] [Indexed: 01/08/2023] Open
Abstract
The genome of the cell is often exposed to DNA damaging agents and therefore requires an intricate well-regulated DNA damage response (DDR) to overcome its deleterious effects. The DDR needs proper regulation for its timely activation, repression, as well as appropriate choice of repair pathway. Studies in Saccharomyces cerevisiae have advanced our understanding of the DNA damage response, as well as the mechanisms the cell employs to maintain genome stability and how these mechanisms are regulated. Eukaryotic cells utilize post-translational modifications as a means for fine-tuning protein functions. Ubiquitylation and SUMOylation involve the attachment of small protein molecules onto proteins to modulate function or protein–protein interactions. SUMO in particular, was shown to act as a molecular glue when DNA damage occurs, facilitating the assembly of large protein complexes in repair foci. In other instances, SUMOylation alters a protein's biochemical activities, and interactions. SUMO-targeted ubiquitin ligases (STUbLs) are enzymes that target SUMOylated proteins for ubiquitylation and subsequent degradation, providing a function for the SUMO modification in the regulation and disassembly of repair complexes. Here, we discuss the major contributions of SUMO and STUbLs in the regulation of DNA damage repair pathways as well as in the maintenance of critical regions of the genome, namely rDNA regions, telomeres and the 2 μm circle in budding yeast.
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Affiliation(s)
- Deena Jalal
- Department of Biochemistry, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al-Ain, UAE
| | - Jisha Chalissery
- Department of Biochemistry, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al-Ain, UAE
| | - Ahmed H Hassan
- Department of Biochemistry, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al-Ain, UAE
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20
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Forsburg SL, Shen KF. Centromere Stability: The Replication Connection. Genes (Basel) 2017; 8:genes8010037. [PMID: 28106789 PMCID: PMC5295031 DOI: 10.3390/genes8010037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 11/16/2022] Open
Abstract
The fission yeast centromere, which is similar to metazoan centromeres, contains highly repetitive pericentromere sequences that are assembled into heterochromatin. This is required for the recruitment of cohesin and proper chromosome segregation. Surprisingly, the pericentromere replicates early in the S phase. Loss of heterochromatin causes this domain to become very sensitive to replication fork defects, leading to gross chromosome rearrangements. This review examines the interplay between components of DNA replication, heterochromatin assembly, and cohesin dynamics that ensures maintenance of genome stability and proper chromosome segregation.
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Affiliation(s)
- Susan L Forsburg
- Program in Molecular & Computational Biology, University of Southern California, Los Angeles, CA 90089-2910, USA.
| | - Kuo-Fang Shen
- Program in Molecular & Computational Biology, University of Southern California, Los Angeles, CA 90089-2910, USA.
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21
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Lin SJ, Tapia-Alveal C, Jabado OJ, Germain D, O'Connell MJ. An acetyltransferase-independent function of Eso1 regulates centromere cohesion. Mol Biol Cell 2016; 27:4002-4010. [PMID: 27798241 PMCID: PMC5156541 DOI: 10.1091/mbc.e16-08-0596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 10/11/2016] [Accepted: 10/12/2016] [Indexed: 12/21/2022] Open
Abstract
Eukaryotes contain three essential Structural Maintenance of Chromosomes (SMC) complexes: cohesin, condensin, and Smc5/6. Cohesin forms a ring-shaped structure that embraces sister chromatids to promote their cohesion. The cohesiveness of cohesin is promoted by acetylation of N-terminal lysines of the Smc3 subunit by the acetyltransferases Eco1 in Saccharomyces cerevisiae and the homologue, Eso1, in Schizosaccharomyces pombe. In both yeasts, these acetyltransferases are essential for cell viability. However, whereas nonacetylatable Smc3 mutants are lethal in S. cerevisiae, they are not in S. pombe We show that the lethality of a temperature-sensitive allele of eso1 (eso1-H17) is due to activation of the spindle assembly checkpoint (SAC) and is associated with premature centromere separation. The lack of cohesion at the centromeres does not correlate with Psm3 acetylation or cohesin levels at the centromeres, but is associated ith significantly reduced recruitment of the cohesin regulator Pds5. The SAC activation in this context is dependent on Smc5/6 function, which is required to remove cohesin from chromosome arms but not centromeres. The mitotic defects caused by Smc5/6 and Eso1 dysfunction are cosuppressed in double mutants. This identifies a novel function (or functions) for Eso1 and Smc5/6 at centromeres and extends the functional relationships between these SMC complexes.
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Affiliation(s)
- Su-Jiun Lin
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Claudia Tapia-Alveal
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Omar J Jabado
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Doris Germain
- Department of Hematology and Oncology, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Matthew J O'Connell
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
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22
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Abstract
SMC (structural maintenance of chromosomes) complexes - which include condensin, cohesin and the SMC5-SMC6 complex - are major components of chromosomes in all living organisms, from bacteria to humans. These ring-shaped protein machines, which are powered by ATP hydrolysis, topologically encircle DNA. With their ability to hold more than one strand of DNA together, SMC complexes control a plethora of chromosomal activities. Notable among these are chromosome condensation and sister chromatid cohesion. Moreover, SMC complexes have an important role in DNA repair. Recent mechanistic insight into the function and regulation of these universal chromosomal machines enables us to propose molecular models of chromosome structure, dynamics and function, illuminating one of the fundamental entities in biology.
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23
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Nie M, Boddy MN. Cooperativity of the SUMO and Ubiquitin Pathways in Genome Stability. Biomolecules 2016; 6:14. [PMID: 26927199 PMCID: PMC4808808 DOI: 10.3390/biom6010014] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 02/17/2016] [Accepted: 02/23/2016] [Indexed: 01/27/2023] Open
Abstract
Covalent attachment of ubiquitin (Ub) or SUMO to DNA repair proteins plays critical roles in maintaining genome stability. These structurally related polypeptides can be viewed as distinct road signs, with each being read by specific protein interaction motifs. Therefore, via their interactions with selective readers in the proteome, ubiquitin and SUMO can elicit distinct cellular responses, such as directing DNA lesions into different repair pathways. On the other hand, through the action of the SUMO-targeted ubiquitin ligase (STUbL) family proteins, ubiquitin and SUMO can cooperate in the form of a hybrid signal. These mixed SUMO-ubiquitin chains recruit “effector” proteins such as the AAA+ ATPase Cdc48/p97-Ufd1-Npl4 complex that contain both ubiquitin and SUMO interaction motifs. This review will summarize recent key findings on collaborative and distinct roles that ubiquitin and SUMO play in orchestrating DNA damage responses.
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Affiliation(s)
- Minghua Nie
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Michael N Boddy
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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24
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Zabrady K, Adamus M, Vondrova L, Liao C, Skoupilova H, Novakova M, Jurcisinova L, Alt A, Oliver AW, Lehmann AR, Palecek JJ. Chromatin association of the SMC5/6 complex is dependent on binding of its NSE3 subunit to DNA. Nucleic Acids Res 2016; 44:1064-79. [PMID: 26446992 PMCID: PMC4756808 DOI: 10.1093/nar/gkv1021] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 09/23/2015] [Accepted: 09/26/2015] [Indexed: 11/13/2022] Open
Abstract
SMC5/6 is a highly conserved protein complex related to cohesin and condensin, which are the key components of higher-order chromatin structures. The SMC5/6 complex is essential for proliferation in yeast and is involved in replication fork stability and processing. However, the precise mechanism of action of SMC5/6 is not known. Here we present evidence that the NSE1/NSE3/NSE4 sub-complex of SMC5/6 binds to double-stranded DNA without any preference for DNA-replication/recombination intermediates. Mutations of key basic residues within the NSE1/NSE3/NSE4 DNA-binding surface reduce binding to DNA in vitro. Their introduction into the Schizosaccharomyces pombe genome results in cell death or hypersensitivity to DNA damaging agents. Chromatin immunoprecipitation analysis of the hypomorphic nse3 DNA-binding mutant shows a reduced association of fission yeast SMC5/6 with chromatin. Based on our results, we propose a model for loading of the SMC5/6 complex onto the chromatin.
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Affiliation(s)
- Katerina Zabrady
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, 62500, Czech Republic Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, Brno, 61137, Czech Republic
| | - Marek Adamus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, 62500, Czech Republic
| | - Lucie Vondrova
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, 62500, Czech Republic Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, Brno, 61137, Czech Republic
| | - Chunyan Liao
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom
| | - Hana Skoupilova
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, Brno, 61137, Czech Republic
| | - Marketa Novakova
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, Brno, 61137, Czech Republic
| | - Lenka Jurcisinova
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, 62500, Czech Republic Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, Brno, 61137, Czech Republic
| | - Aaron Alt
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom
| | - Antony W Oliver
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom
| | - Alan R Lehmann
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom
| | - Jan J Palecek
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, 62500, Czech Republic Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlarska 2, Brno, 61137, Czech Republic
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25
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Jacome A, Gutierrez-Martinez P, Schiavoni F, Tenaglia E, Martinez P, Rodríguez-Acebes S, Lecona E, Murga M, Méndez J, Blasco MA, Fernandez-Capetillo O. NSMCE2 suppresses cancer and aging in mice independently of its SUMO ligase activity. EMBO J 2015; 34:2604-19. [PMID: 26443207 DOI: 10.15252/embj.201591829] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 09/01/2015] [Indexed: 01/16/2023] Open
Abstract
The SMC5/6 complex is the least understood of SMC complexes. In yeast, smc5/6 mutants phenocopy mutations in sgs1, the BLM ortholog that is deficient in Bloom's syndrome (BS). We here show that NSMCE2 (Mms21, in Saccharomyces cerevisiae), an essential SUMO ligase of the SMC5/6 complex, suppresses cancer and aging in mice. Surprisingly, a mutation that compromises NSMCE2-dependent SUMOylation does not have a detectable impact on murine lifespan. In contrast, NSMCE2 deletion in adult mice leads to pathologies resembling those found in patients of BS. Moreover, and whereas NSMCE2 deletion does not have a detectable impact on DNA replication, NSMCE2-deficient cells also present the cellular hallmarks of BS such as increased recombination rates and an accumulation of micronuclei. Despite the similarities, NSMCE2 and BLM foci do not colocalize and concomitant deletion of Blm and Nsmce2 in B lymphocytes further increases recombination rates and is synthetic lethal due to severe chromosome mis-segregation. Our work reveals that SUMO- and BLM-independent activities of NSMCE2 limit recombination and facilitate segregation; functions of the SMC5/6 complex that are necessary to prevent cancer and aging in mice.
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Affiliation(s)
- Ariana Jacome
- Genomic Instability Group, Spanish National Cancer Research Centre, Madrid, Spain
| | | | - Federica Schiavoni
- Genomic Instability Group, Spanish National Cancer Research Centre, Madrid, Spain
| | - Enrico Tenaglia
- Genomic Instability Group, Spanish National Cancer Research Centre, Madrid, Spain
| | - Paula Martinez
- Telomeres and Telomerase Group, Spanish National Cancer Research Centre, Madrid, Spain
| | | | - Emilio Lecona
- Genomic Instability Group, Spanish National Cancer Research Centre, Madrid, Spain
| | - Matilde Murga
- Genomic Instability Group, Spanish National Cancer Research Centre, Madrid, Spain
| | - Juan Méndez
- DNA Replication Group, Spanish National Cancer Research Centre, Madrid, Spain
| | - Maria A Blasco
- Telomeres and Telomerase Group, Spanish National Cancer Research Centre, Madrid, Spain
| | - Oscar Fernandez-Capetillo
- Genomic Instability Group, Spanish National Cancer Research Centre, Madrid, Spain Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
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26
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Mec1-dependent phosphorylation of Mms21 modulates its SUMO ligase activity. DNA Repair (Amst) 2015; 28:83-92. [DOI: 10.1016/j.dnarep.2015.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 01/12/2015] [Accepted: 01/15/2015] [Indexed: 12/25/2022]
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27
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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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28
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Bermúdez-López M, Pociño-Merino I, Sánchez H, Bueno A, Guasch C, Almedawar S, Bru-Virgili S, Garí E, Wyman C, Reverter D, Colomina N, Torres-Rosell J. ATPase-dependent control of the Mms21 SUMO ligase during DNA repair. PLoS Biol 2015; 13:e1002089. [PMID: 25764370 PMCID: PMC4357442 DOI: 10.1371/journal.pbio.1002089] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 01/26/2015] [Indexed: 11/18/2022] Open
Abstract
Modification of proteins by SUMO is essential for the maintenance of genome integrity. During DNA replication, the Mms21-branch of the SUMO pathway counteracts recombination intermediates at damaged replication forks, thus facilitating sister chromatid disjunction. The Mms21 SUMO ligase docks to the arm region of the Smc5 protein in the Smc5/6 complex; together, they cooperate during recombinational DNA repair. Yet how the activity of the SUMO ligase is controlled remains unknown. Here we show that the SUMO ligase and the chromosome disjunction functions of Mms21 depend on its docking to an intact and active Smc5/6 complex, indicating that the Smc5/6-Mms21 complex operates as a large SUMO ligase in vivo. In spite of the physical distance separating the E3 and the nucleotide-binding domains in Smc5/6, Mms21-dependent sumoylation requires binding of ATP to Smc5, a step that is part of the ligase mechanism that assists Ubc9 function. The communication is enabled by the presence of a conserved disruption in the coiled coil domain of Smc5, pointing to potential conformational changes for SUMO ligase activation. In accordance, scanning force microscopy of the Smc5-Mms21 heterodimer shows that the molecule is physically remodeled in an ATP-dependent manner. Our results demonstrate that the ATP-binding activity of the Smc5/6 complex is coordinated with its SUMO ligase, through the coiled coil domain of Smc5 and the physical remodeling of the molecule, to promote sumoylation and chromosome disjunction during DNA repair. Conserved conformational joints in the Mms21-Smc5/6 complex allow coordination between its ATPase and E3 SUMO ligase activities, integrating its structural and signaling roles during DNA repair to allow correct chromosome separation. The modification of target proteins by conjugation to SUMO—a small protein that acts as a regulatory tag—is essential for maintaining the integrity of genomes in most eukaryotic organisms. One critical step during the attachment of SUMO is the activation of the enzymes that catalyze this reaction—E1, E2, and the SUMO ligases. However, we currently do not fully understand how the different enzymes in the SUMO pathway are regulated. The SUMO ligase Mms21 is known to bind to Smc5/6, a large protein complex involved in the structural maintenance of chromosomes. Both Mms21 and Smc5/6 counteract the accumulation of recombination intermediates, which otherwise join replicated chromosomes, preventing their separation. Not surprisingly, the few known targets of the Mms21 ligase are mostly related to the repair of sister chromatids by recombination. Here, we show that the Mms21 SUMO ligase needs to bind to the Smc5/6 complex to promote chromosome separation. We used two Mms21-dependent SUMO conjugation targets—Smc5 and cohesin—to study the connection between the Mms21’s SUMO ligase activity and its binding partner, Smc5/6. Our results indicated that Mms21 activation is tightly coordinated with the intrinsic ATPase function of the Smc5/6 complex. However, the SUMO ligase and the ATPase lie in different domains of the Smc5/6-Mms21 complex that are normally distant from each other; we show that communication between these enzyme sites is enabled by the presence of conserved joints, which we suggest allow the necessary conformational changes required for SUMO ligase activation. This coordination of activities is extremely helpful for the cell, enabling it to integrate a structural role on chromatin during DNA repair with a signaling function, thereby promoting correct separation of the chromosomes.
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Affiliation(s)
| | - Irene Pociño-Merino
- IRBLLEIDA, Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - Humberto Sánchez
- Department of Genetics and Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Andrés Bueno
- IRBLLEIDA, Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - Clàudia Guasch
- IRBLLEIDA, Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - Seba Almedawar
- IRBLLEIDA, Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - Sergi Bru-Virgili
- Institut de Biotecnologia i Biomedicina, Dept. de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Eloi Garí
- IRBLLEIDA, Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - Claire Wyman
- Department of Genetics and Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - David Reverter
- Institut de Biotecnologia i Biomedicina, Dept. de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Neus Colomina
- IRBLLEIDA, Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - Jordi Torres-Rosell
- IRBLLEIDA, Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
- * E-mail:
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29
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The maintenance of chromosome structure: positioning and functioning of SMC complexes. Nat Rev Mol Cell Biol 2014; 15:601-14. [PMID: 25145851 DOI: 10.1038/nrm3857] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Structural maintenance of chromosomes (SMC) complexes, which in eukaryotic cells include cohesin, condensin and the Smc5/6 complex, are central regulators of chromosome dynamics and control sister chromatid cohesion, chromosome condensation, DNA replication, DNA repair and transcription. Even though the molecular mechanisms that lead to this large range of functions are still unclear, it has been established that the complexes execute their functions through their association with chromosomal DNA. A large set of data also indicates that SMC complexes work as intermolecular and intramolecular linkers of DNA. When combining these insights with results from ongoing analyses of their chromosomal binding, and how this interaction influences the structure and dynamics of chromosomes, a picture of how SMC complexes carry out their many functions starts to emerge.
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30
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Tapia-Alveal C, Lin SJ, O’Connell MJ. Functional interplay between cohesin and Smc5/6 complexes. Chromosoma 2014; 123:437-45. [PMID: 24981336 PMCID: PMC4169997 DOI: 10.1007/s00412-014-0474-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 06/10/2014] [Accepted: 06/11/2014] [Indexed: 12/14/2022]
Abstract
Chromosomes are subjected to massive reengineering as they are replicated, transcribed, repaired, condensed, and segregated into daughter cells. Among the engineers are three large protein complexes collectively known as the structural maintenance of chromosome (SMC) complexes: cohesin, condensin, and Smc5/6. As their names suggest, cohesin controls sister chromatid cohesion, condensin controls chromosome condensation, and while precise functions for Smc5/6 have remained somewhat elusive, most reports have focused on the control of recombinational DNA repair. Here, we focus on cohesin and Smc5/6 function. It is becoming increasingly clear that the functional repertoires of these complexes are greater than sister chromatid cohesion and recombination. These SMC complexes are emerging as interrelated and cooperating factors that control chromosome dynamics throughout interphase. However, they also release their embrace of sister chromatids to enable their segregation at anaphase, resetting the dynamic cycle of SMC-chromosome interactions.
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Affiliation(s)
- Claudia Tapia-Alveal
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Su-Jiun Lin
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Matthew J. O’Connell
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
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31
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Abstract
Replication stress is a significant contributor to genome instability. Recent studies suggest that the centromere is particularly susceptible to replication stress and prone to rearrangements and genome damage, as well as chromosome loss. This effect is enhanced by loss of heterochromatin. The resulting changes in genetic organization, including chromosome loss, increased mutation and loss of heterozygosity, are important contributors to malignant growth.
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32
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Laflamme G, Tremblay-Boudreault T, Roy MA, Andersen P, Bonneil É, Atchia K, Thibault P, D'Amours D, Kwok BH. Structural maintenance of chromosome (SMC) proteins link microtubule stability to genome integrity. J Biol Chem 2014; 289:27418-31. [PMID: 25135640 DOI: 10.1074/jbc.m114.569608] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Structural maintenance of chromosome (SMC) proteins are key organizers of chromosome architecture and are essential for genome integrity. They act by binding to chromatin and connecting distinct parts of chromosomes together. Interestingly, their potential role in providing connections between chromatin and the mitotic spindle has not been explored. Here, we show that yeast SMC proteins bind directly to microtubules and can provide a functional link between microtubules and DNA. We mapped the microtubule-binding region of Smc5 and generated a mutant with impaired microtubule binding activity. This mutant is viable in yeast but exhibited a cold-specific conditional lethality associated with mitotic arrest, aberrant spindle structures, and chromosome segregation defects. In an in vitro reconstitution assay, this Smc5 mutant also showed a compromised ability to protect microtubules from cold-induced depolymerization. Collectively, these findings demonstrate that SMC proteins can bind to and stabilize microtubules and that SMC-microtubule interactions are essential to establish a robust system to maintain genome integrity.
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Affiliation(s)
- Guillaume Laflamme
- From the Chemical Biology of Cell Division Laboratory, the Laboratory of Cell Cycle Regulation and Chromosome Structure, and
| | | | - Marc-André Roy
- the Laboratory of Cell Cycle Regulation and Chromosome Structure, and
| | | | - Éric Bonneil
- the Laboratory of Proteomics and Bioanalytical Mass Spectrometry, Institute for Research in Immunology and Cancer, and
| | - Kaleem Atchia
- From the Chemical Biology of Cell Division Laboratory
| | - Pierre Thibault
- the Laboratory of Proteomics and Bioanalytical Mass Spectrometry, Institute for Research in Immunology and Cancer, and the Departments of Chemistry
| | - Damien D'Amours
- the Laboratory of Cell Cycle Regulation and Chromosome Structure, and Pathology and Cellular Biology, and
| | - Benjamin H Kwok
- From the Chemical Biology of Cell Division Laboratory, Medicine, Université de Montréal, Station Centre-Ville, Montréal, Québec H3C 3J7, Canada
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33
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Tapia-Alveal C, Lin SJ, Yeoh A, Jabado OJ, O'Connell MJ. H2A.Z-dependent regulation of cohesin dynamics on chromosome arms. Mol Cell Biol 2014; 34:2092-104. [PMID: 24687850 PMCID: PMC4019066 DOI: 10.1128/mcb.00193-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 02/25/2014] [Accepted: 03/21/2014] [Indexed: 11/20/2022] Open
Abstract
Structural maintenance of chromosomes (SMC) complexes and DNA topoisomerases are major determinants of chromosome structure and dynamics. The cohesin complex embraces sister chromatids throughout interphase, but during mitosis most cohesin is stripped from chromosome arms by early prophase, while the remaining cohesin at kinetochores is cleaved at anaphase. This two-step removal of cohesin is required for sister chromatids to separate. The cohesin-related Smc5/6 complex has been studied mostly as a determinant of DNA repair via homologous recombination. However, chromosome segregation fails in Smc5/6 null mutants or cells treated with small interfering RNAs. This also occurs in Smc5/6 hypomorphs in the fission yeast Schizosaccharomyces pombe following genotoxic and replication stress, or topoisomerase II dysfunction, and these mitotic defects are due to the postanaphase retention of cohesin on chromosome arms. Here we show that mitotic and repair roles for Smc5/6 are genetically separable in S. pombe. Further, we identified the histone variant H2A.Z as a critical factor to modulate cohesin dynamics, and cells lacking H2A.Z suppress the mitotic defects conferred by Smc5/6 dysfunction. Together, H2A.Z and the SMC complexes ensure genome integrity through accurate chromosome segregation.
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Affiliation(s)
- Claudia Tapia-Alveal
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Su-Jiun Lin
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Aaron Yeoh
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Omar J. Jabado
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Matthew J. O'Connell
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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34
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Gómez R, Jordan PW, Viera A, Alsheimer M, Fukuda T, Jessberger R, Llano E, Pendás AM, Handel MA, Suja JA. Dynamic localization of SMC5/6 complex proteins during mammalian meiosis and mitosis suggests functions in distinct chromosome processes. J Cell Sci 2013; 126:4239-52. [PMID: 23843628 DOI: 10.1242/jcs.130195] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Four members of the structural maintenance of chromosome (SMC) protein family have essential functions in chromosome condensation (SMC2/4) and sister-chromatid cohesion (SMC1/3). The SMC5/6 complex has been implicated in chromosome replication, DNA repair and chromosome segregation in somatic cells, but its possible functions during mammalian meiosis are unknown. Here, we show in mouse spermatocytes that SMC5 and SMC6 are located at the central region of the synaptonemal complex from zygotene until diplotene. During late diplotene both proteins load to the chromocenters, where they colocalize with DNA Topoisomerase IIα, and then accumulate at the inner domain of the centromeres during the first and second meiotic divisions. Interestingly, SMC6 and DNA Topoisomerase IIα colocalize at stretched strands that join kinetochores during the metaphase II to anaphase II transition, and both are observed on stretched lagging chromosomes at anaphase II following treatment with Etoposide. During mitosis, SMC6 and DNA Topoisomerase IIα colocalize at the centromeres and chromatid axes. Our results are consistent with the participation of SMC5 and SMC6 in homologous chromosome synapsis during prophase I, chromosome and centromere structure during meiosis I and mitosis and, with DNA Topoisomerase IIα, in regulating centromere cohesion during meiosis II.
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Affiliation(s)
- Rocío Gómez
- Departamento de Biología, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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35
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Wang CM, Brennan VC, Gutierrez NM, Wang X, Wang L, Yang WH. SUMOylation of ATF3 alters its transcriptional activity on regulation of TP53 gene. J Cell Biochem 2013; 114:589-98. [PMID: 22991139 DOI: 10.1002/jcb.24396] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 09/07/2012] [Indexed: 12/11/2022]
Abstract
Cyclic AMP-dependent transcription factor-3 (ATF3), a stress sensor, plays an essential role in cells to maintain homeostasis and has diverse functions in cellular survival and death signal pathways. ATF3 is a novel regulator of p53 protein stability and function. The activities of ATF3 are modulated by post-translational modifications (PTMs), such as ubiquitination, but whether it is modified by small ubiquitin-related modifier (SUMO) remains unknown. The aim of this study was to investigate whether ATF3 is post-translationally modified by SUMO proteins and also to elucidate SUMOylation of ATF3 on TP53 gene activity. Here we report that ATF3 is clearly defined as a SUMO target protein both in vitro SUMOylation assay using recombinant proteins and at the cellular levels. Furthermore, ATF3 interacted with UBE2I, the only SUMO E2 enzyme found so far. In addition, PIAS3β (a SUMO E3 ligase) enhanced and SENP2 and SENP7 (two SUMOylation proteases) decreased SUMOylation of ATF3, respectively. Finally, we found that ATF3 is selectively SUMOylated at lysine residue 42 but the SUMOylation does not alter subcellular localization of ATF3. We then characterized the functional role of ATF3 SUMOylation on TP53 gene expression. We found that SUMOylation of ATF3 is required for full repression of TP53 gene. Overall, we provide the first evidence that ATF3 is post-translationally modified by SUMO and SUMOylation of ATF3 plays a functional role in regulation of TP53 gene activity.
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Affiliation(s)
- Chiung-Min Wang
- Department of Biomedical Sciences, Mercer University School of Medicine, Savannah, GA 31404, USA
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36
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Kirkland JG, Kamakaka RT. Long-range heterochromatin association is mediated by silencing and double-strand DNA break repair proteins. ACTA ACUST UNITED AC 2013; 201:809-26. [PMID: 23733345 PMCID: PMC3678155 DOI: 10.1083/jcb.201211105] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In yeast, the localization of homologous recombination–associated proteins to heterochromatic regions of the genome is necessary for proper nuclear organization. The eukaryotic genome is highly organized in the nucleus, and this organization affects various nuclear processes. However, the molecular details of higher-order organization of chromatin remain obscure. In the present study, we show that the Saccharomyces cerevisiae silenced loci HML and HMR cluster in three-dimensional space throughout the cell cycle and independently of the telomeres. Long-range HML–HMR interactions require the homologous recombination (HR) repair pathway and phosphorylated H2A (γ-H2A). γ-H2A is constitutively present at silenced loci in unperturbed cells, its localization requires heterochromatin, and it is restricted to the silenced domain by the transfer DNA boundary element. SMC proteins and Scc2 localize to the silenced domain, and Scc2 binding requires the presence of γ-H2A. These findings illustrate a novel pathway for heterochromatin organization and suggest a role for HR repair proteins in genomic organization.
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Affiliation(s)
- Jacob G Kirkland
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
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37
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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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38
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Wang CM, Yang WH. Loss of SUMOylation on ATF3 inhibits proliferation of prostate cancer cells by modulating CCND1/2 activity. Int J Mol Sci 2013; 14:8367-80. [PMID: 23591848 PMCID: PMC3645748 DOI: 10.3390/ijms14048367] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 03/28/2013] [Accepted: 04/09/2013] [Indexed: 11/30/2022] Open
Abstract
SUMOylation plays an important role in regulating a wide range of cellular processes. Previously, we showed that ATF3, a stress response mediator, can be SUMOylated and lysine 42 is the major SUMO site. However, the significance of ATF3 SUMOylation in biological processes is still poorly understood. In the present study, we investigated the role of ATF3 SUMOylation on CCND activity and cellular proliferation in human prostate cancer cells. First, we showed that ATF3 can be SUMOylated endogenously in the overexpression system, and lysine 42 is the major SUMO site. Unlike normal prostate tissue and androgen-responsive LNCaP cancer cells, androgen-independent PC3 and DU145 cancer cells did not express ATF3 endogenously. Overexpression of ATF3 increased CCND1/2 expression in PC3 and DU145 cancer cells. Interestingly, we observed that SUMOylation is essential for ATF3-mediated CCND1/2 activation. Finally, we observed that SUMOylation plays a functional role in ATF3-mediated cellular proliferation in PC3 and DU145 cells. Taken together, our results demonstrate that SUMO modification of ATF3 influences CCND1/2 activity and cellular proliferation of prostate cancer PC3 and DU145 cells and explains at least in part how ATF3 functions to regulate cancer development.
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Affiliation(s)
- Chiung-Min Wang
- Department of Biomedical Sciences, Mercer University School of Medicine, Savannah, GA 31404, USA.
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39
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Abstract
A major challenge in nuclear organization is the packaging of DNA into dynamic chromatin structures that can respond to changes in the transcriptional requirements of the cell. Posttranslational protein modifications, of histones and other chromatin-associated factors, are essential regulators of chromatin dynamics. In this Review, we summarize studies demonstrating that posttranslational modification of proteins by small ubiquitin-related modifiers (SUMOs) regulates chromatin structure and function at multiple levels and through a variety of mechanisms to influence gene expression and maintain genome integrity.
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Affiliation(s)
- Caelin Cubeñas-Potts
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
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40
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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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41
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Yong-Gonzales V, Hang LE, Castellucci F, Branzei D, Zhao X. The Smc5-Smc6 complex regulates recombination at centromeric regions and affects kinetochore protein sumoylation during normal growth. PLoS One 2012; 7:e51540. [PMID: 23284708 PMCID: PMC3527468 DOI: 10.1371/journal.pone.0051540] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 11/08/2012] [Indexed: 11/22/2022] Open
Abstract
The Smc5-Smc6 complex in Saccharomyces cerevisiae is both essential for growth and important for coping with genotoxic stress. While it facilitates damage tolerance throughout the genome under genotoxin treatment, its function during unperturbed growth is mainly documented for repetitive DNA sequence maintenance. Here we provide physical and genetic evidence showing that the Smc5–Smc6 complex regulates recombination at non-repetitive loci such as centromeres in the absence of DNA damaging agents. Mutating Smc6 results in the accumulation of recombination intermediates at centromeres and other unique sequences as assayed by 2D gel analysis. In addition, smc6 mutant cells exhibit increased levels of Rad52 foci that co-localize with centromere markers. A rad52 mutation that decreases centromeric, but not overall, levels of Rad52 foci in smc6 mutants suppresses the nocodazole sensitivity of these cells, suggesting that the Smc6-mediated regulation of recombination at centromeric regions impacts centromere-related functions. In addition to influencing recombination, the SUMO ligase subunit of the Smc5–Smc6 complex promotes the sumoylation of two kinetochore proteins and affects mitotic spindles. These results suggest that the Smc5–Smc6 complex regulates both recombination and kinetochore sumoylation to facilitate chromosomal maintenance during growth.
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Affiliation(s)
- Vladimir Yong-Gonzales
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Lisa E. Hang
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
- Programs in Biochemistry, Cell and Molecular Biology, Weill Cornell Graduate School of Medical Sciences, New York, New York, United States of America
| | | | - Dana Branzei
- IFOM, FIRC Institute of Molecular Oncology, Milan, Italy
| | - Xiaolan Zhao
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
- * E-mail:
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42
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Altmannová V, Kolesár P, Krejčí L. SUMO Wrestles with Recombination. Biomolecules 2012; 2:350-75. [PMID: 24970142 PMCID: PMC4030836 DOI: 10.3390/biom2030350] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Revised: 06/27/2012] [Accepted: 07/13/2012] [Indexed: 01/21/2023] Open
Abstract
DNA double-strand breaks (DSBs) comprise one of the most toxic DNA lesions, as the failure to repair a single DSB has detrimental consequences on the cell. Homologous recombination (HR) constitutes an error-free repair pathway for the repair of DSBs. On the other hand, when uncontrolled, HR can lead to genome rearrangements and needs to be tightly regulated. In recent years, several proteins involved in different steps of HR have been shown to undergo modification by small ubiquitin-like modifier (SUMO) peptide and it has been suggested that deficient sumoylation impairs the progression of HR. This review addresses specific effects of sumoylation on the properties of various HR proteins and describes its importance for the homeostasis of DNA repetitive sequences. The article further illustrates the role of sumoylation in meiotic recombination and the interplay between SUMO and other post-translational modifications.
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Affiliation(s)
| | - Peter Kolesár
- Department of Biology, Masaryk University, Brno 62500, Czech Republic.
| | - Lumír Krejčí
- Department of Biology, Masaryk University, Brno 62500, Czech Republic.
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43
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Bustard DE, Menolfi D, Jeppsson K, Ball LG, Dewey SC, Shirahige K, Sjögren C, Branzei D, Cobb JA. During replication stress, non-SMC element 5 (NSE5) is required for Smc5/6 protein complex functionality at stalled forks. J Biol Chem 2012; 287:11374-83. [PMID: 22303010 DOI: 10.1074/jbc.m111.336263] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The Smc5/6 complex belongs to the SMC (structural maintenance of chromosomes) family, which also includes cohesin and condensin. In Saccharomyces cerevisiae, the Smc5/6 complex contains six essential non-Smc elements, Nse1-6. Very little is known about how these additional elements contribute to complex function except for Nse2/Mms21, which is an E3 small ubiquitin-like modifier (SUMO) ligase important for Smc5 sumoylation. Characterization of two temperature-sensitive mutants, nse5-ts1 and nse5-ts2, demonstrated the importance of Nse5 within the Smc5/6 complex for its stability and functionality at forks during hydroxyurea-induced replication stress. Both NSE5 alleles showed a marked reduction in Smc5 sumoylation to levels lower than those observed with mms21-11, a mutant of Mms21 that is deficient in SUMO ligase activity. However, a phenotypic comparison of nse5-ts1 and nse5-ts2 revealed a separation of importance between Smc5 sumoylation and the function of the Smc5/6 complex during replication. Only cells carrying the nse5-ts1 allele exhibited defects such as dissociation of the replisome from stalled forks, formation of fork-associated homologous recombination intermediates, and hydroxyurea sensitivity that is additive with mms21-11. These defects are attributed to a failure in Smc5/6 localization to forks in nse5-ts1 cells. Overall, these data support the premise that Nse5 is important for vital interactions between components within the Smc5/6 complex, and for its functionality during replication stress.
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Affiliation(s)
- Denise E Bustard
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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44
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DNA-binding properties of Smc6, a core component of the Smc5-6 DNA repair complex. Biochem Biophys Res Commun 2011; 416:80-5. [PMID: 22086171 DOI: 10.1016/j.bbrc.2011.10.149] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 10/31/2011] [Indexed: 11/22/2022]
Abstract
The Smc5-6 complex is an essential regulator of chromosome integrity and a key component of the DNA damage response. As an essential DNA repair factor, the Smc5-6 complex is expected to interact with DNA and/or chromatin during the execution of its functions. How the Smc6 protein promotes the binding of the Smc5-6 complex to DNA lesions is currently unknown. We show here that Smc6 is a strong DNA-binding protein with a clear preference for single-stranded DNA substrates. Importantly, Smc6 associates with DNA in the absence of other Smc5-6 complex components and its activity is modulated by nucleotides. Our results also show that the minimal size of single-stranded DNA required for tight association with Smc6 is ~60 nucleotides in length. Taken together, our results suggest that Smc6 contributes to DNA repair in vivo by targeting the Smc5-6 complex to single-stranded DNA substrates created during the processes of homologous recombination and/or DNA replication.
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45
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Tapia-Alveal C, O'Connell MJ. Nse1-dependent recruitment of Smc5/6 to lesion-containing loci contributes to the repair defects of mutant complexes. Mol Biol Cell 2011; 22:4669-82. [PMID: 21976700 PMCID: PMC3226483 DOI: 10.1091/mbc.e11-03-0272] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The Smc5/6 complex is widely believed to be required for homologous recombination. It is shown that repair defects of Smc5/6 mutants are due to the Nse1-dependent recruitment of dysfunctional complexes to lesions. Of the three structural maintenance of chromosomes (SMC) complexes, Smc5/6 remains the most poorly understood. Genetic studies have shown that Smc5/6 mutants are defective in homologous recombination (HR), and consistent with this, Smc5/6 is enriched at lesions. However, Smc5/6 is essential for viability, but HR is not, and the terminal phenotype of null Smc5/6 mutants is mitotic failure. Here we analyze the function of Nse1, which contains a variant RING domain that is characteristic of ubiquitin ligases. Whereas deletion of this domain causes DNA damage sensitivity and mitotic failure, serine mutations in conserved cysteines do not. However, these mutations suppress the DNA damage sensitivity of Smc5/6 hypomorphs but not that of HR mutants and remarkably decrease the recruitment of Smc5/6 to loci containing lesions marked for HR-mediated repair. Analysis of DNA repair pathways in suppressed double mutants suggests that lesions are channeled into recombination-dependent and error-free postreplication repair. Thus the HR defect in Smc5/6 mutants appears to be due to the presence of dysfunctional complexes at lesions rather than to reflect an absolute requirement for Smc5/6 to complete HR.
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Affiliation(s)
- Claudia Tapia-Alveal
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, NY 10029, USA
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46
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De S, Varsally W, Falciani F, Brogna S. Ribosomal proteins' association with transcription sites peaks at tRNA genes in Schizosaccharomyces pombe. RNA (NEW YORK, N.Y.) 2011; 17:1713-26. [PMID: 21757508 PMCID: PMC3162336 DOI: 10.1261/rna.2808411] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2011] [Accepted: 06/13/2011] [Indexed: 05/05/2023]
Abstract
Ribosomal proteins (RPs) are essential components of ribosomes, but several RPs are also present at transcription sites of eukaryotic chromosomes. Here, we report a genome-wide ChIP-on-chip analysis of the association of three representative 60S RPs with sites in the Schizosaccharomyces pombe chromosomes. All three proteins tend to bind at the same subset of coding and noncoding loci. The data demonstrate selective RNA-dependent interactions between RPs and many transcription sites and suggest that the RPs bind as components of a preassembled multiprotein complex, perhaps 60S or pre-60S subunits. These findings further indicate that the presence of RPs complexes at transcription sites might be a general feature of eukaryotic cells and functionally important. Unexpectedly, the RPs' chromosomal association is highest at centromeres and tRNA genes-the RPs were found at 167 of the 171 tRNA genes assayed. These findings raise the intriguing possibility that RP complexes are involved in tRNA biogenesis and possibly centromere functions.
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Affiliation(s)
- Sandip De
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Wazeer Varsally
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Francesco Falciani
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Saverio Brogna
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
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47
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Dheekollu J, Wiedmer A, Hayden J, Speicher D, Gotter AL, Yen T, Lieberman PM. Timeless links replication termination to mitotic kinase activation. PLoS One 2011; 6:e19596. [PMID: 21573113 PMCID: PMC3089618 DOI: 10.1371/journal.pone.0019596] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 04/01/2011] [Indexed: 02/04/2023] Open
Abstract
The mechanisms that coordinate the termination of DNA replication with progression through mitosis are not completely understood. The human Timeless protein (Tim) associates with S phase replication checkpoint proteins Claspin and Tipin, and plays an important role in maintaining replication fork stability at physical barriers, like centromeres, telomeres and ribosomal DNA repeats, as well as at termination sites. We show here that human Tim can be isolated in a complex with mitotic entry kinases CDK1, Auroras A and B, and Polo-like kinase (Plk1). Plk1 bound Tim directly and colocalized with Tim at a subset of mitotic structures in M phase. Tim depletion caused multiple mitotic defects, including the loss of sister-chromatid cohesion, loss of mitotic spindle architecture, and a failure to exit mitosis. Tim depletion caused a delay in mitotic kinase activity in vivo and in vitro, as well as a reduction in global histone H3 S10 phosphorylation during G2/M phase. Tim was also required for the recruitment of Plk1 to centromeric DNA and formation of catenated DNA structures at human centromere alpha satellite repeats. Taken together, these findings suggest that Tim coordinates mitotic kinase activation with termination of DNA replication.
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Affiliation(s)
- Jayaraju Dheekollu
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Andreas Wiedmer
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - James Hayden
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - David Speicher
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Anthony L. Gotter
- Merk Research Laboratories, West Point, Pennsylvania, United States of America
| | - Tim Yen
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| | - Paul M. Lieberman
- The Wistar Institute, Philadelphia, Pennsylvania, United States of America
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The Nse2/Mms21 SUMO ligase of the Smc5/6 complex in the maintenance of genome stability. FEBS Lett 2011; 585:2907-13. [PMID: 21550342 DOI: 10.1016/j.febslet.2011.04.067] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 04/22/2011] [Accepted: 04/27/2011] [Indexed: 01/21/2023]
Abstract
There exist three highly-conserved structural maintenance of chromosomes (Smc) complexes that ensure genome stability during eukaryotic cell division. There are the well-characterized cohesin and condensin complexes and the third Smc complex, Smc5/6. Nse2/Mms21, a SUMO ligase, is a component of the Smc5/6 complex and recent data have indicated that Nse1 may function as a ubiquitin ligase. Smc5/6 regulates sister chromatid cohesion, homologous recombination and chromatin structure and conformation. This review examines the functions of Smc5/6 in DNA repair and the maintenance of genomic integrity and explores the roles of the associated SUMO and ubiquitin ligases. Recent findings have indicated that Smc5/6 may play a topological role in chromosome dynamics, which may help understand the complexity of its activities.
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SUMO-targeted ubiquitin ligase, Rad60, and Nse2 SUMO ligase suppress spontaneous Top1-mediated DNA damage and genome instability. PLoS Genet 2011; 7:e1001320. [PMID: 21408210 PMCID: PMC3048374 DOI: 10.1371/journal.pgen.1001320] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 01/26/2011] [Indexed: 11/19/2022] Open
Abstract
Through as yet undefined proteins and pathways, the SUMO-targeted ubiquitin ligase (STUbL) suppresses genomic instability by ubiquitinating SUMO conjugated proteins and driving their proteasomal destruction. Here, we identify a critical function for fission yeast STUbL in suppressing spontaneous and chemically induced topoisomerase I (Top1)-mediated DNA damage. Strikingly, cells with reduced STUbL activity are dependent on tyrosyl-DNA phosphodiesterase 1 (Tdp1). This is notable, as cells lacking Tdp1 are largely aphenotypic in the vegetative cell cycle due to the existence of alternative pathways for the removal of covalent Top1-DNA adducts (Top1cc). We further identify Rad60, a SUMO mimetic and STUbL-interacting protein, and the SUMO E3 ligase Nse2 as critical Top1cc repair factors in cells lacking Tdp1. Detection of Top1ccs using chromatin immunoprecipitation and quantitative PCR shows that they are elevated in cells lacking Tdp1 and STUbL, Rad60, or Nse2 SUMO ligase activity. These unrepaired Top1ccs are shown to cause DNA damage, hyper-recombination, and checkpoint-mediated cell cycle arrest. We further determine that Tdp1 and the nucleotide excision repair endonuclease Rad16-Swi10 initiate the major Top1cc repair pathways of fission yeast. Tdp1-based repair is the predominant activity outside S phase, likely acting on transcription-coupled Top1cc. Epistasis analyses suggest that STUbL, Rad60, and Nse2 facilitate the Rad16-Swi10 pathway, parallel to Tdp1. Collectively, these results reveal a unified role for STUbL, Rad60, and Nse2 in protecting genome stability against spontaneous Top1-mediated DNA damage.
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50
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Double-strand breaks in heterochromatin move outside of a dynamic HP1a domain to complete recombinational repair. Cell 2011; 144:732-44. [PMID: 21353298 DOI: 10.1016/j.cell.2011.02.012] [Citation(s) in RCA: 396] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 12/15/2010] [Accepted: 02/07/2011] [Indexed: 01/07/2023]
Abstract
Double-strand breaks (DSBs) in heterochromatic repetitive DNAs pose significant threats to genome integrity, but information about how such lesions are processed and repaired is sparse. We observe dramatic expansion and dynamic protrusions of the heterochromatin domain in response to ionizing radiation (IR) in Drosophila cells. We also find that heterochromatic DSBs are repaired by homologous recombination (HR) but with striking differences from euchromatin. Proteins involved in early HR events (resection) are rapidly recruited to DSBs within heterochromatin. In contrast, Rad51, which mediates strand invasion, only associates with DSBs that relocalize outside of the domain. Heterochromatin expansion and relocalization of foci require checkpoint and resection proteins. Finally, the Smc5/6 complex is enriched in heterochromatin and is required to exclude Rad51 from the domain and prevent abnormal recombination. We propose that the spatial and temporal control of DSB repair in heterochromatin safeguards genome stability by preventing aberrant exchanges between repeats.
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