1
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Thu YM. Multifaceted roles of SUMO in DNA metabolism. Nucleus 2024; 15:2398450. [PMID: 39287196 PMCID: PMC11409511 DOI: 10.1080/19491034.2024.2398450] [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: 06/26/2024] [Revised: 08/16/2024] [Accepted: 08/26/2024] [Indexed: 09/19/2024] Open
Abstract
Sumoylation, a process in which SUMO (small ubiquitin like modifier) is conjugated to target proteins, emerges as a post-translational modification that mediates protein-protein interactions, protein complex assembly, and localization of target proteins. The coordinated actions of SUMO ligases, proteases, and SUMO-targeted ubiquitin ligases determine the net result of sumoylation. It is well established that sumoylation can somewhat promiscuously target proteins in groups as well as selectively target individual proteins. Through changing protein dynamics, sumoylation orchestrates multi-step processes in chromatin biology. Sumoylation influences various steps of mitosis, DNA replication, DNA damage repair, and pathways protecting chromosome integrity. This review highlights examples of SUMO-regulated nuclear processes to provide mechanistic views of sumoylation in DNA metabolism.
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Affiliation(s)
- Yee Mon Thu
- Department of Biology, Colby College, Waterville, ME, USA
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2
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Her J, Zheng H, Bunting SF. RNF4 sustains Myc-driven tumorigenesis by facilitating DNA replication. J Clin Invest 2024; 134:e167419. [PMID: 38530355 PMCID: PMC11093604 DOI: 10.1172/jci167419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 03/20/2024] [Indexed: 03/27/2024] Open
Abstract
The mammalian SUMO-targeted E3 ubiquitin ligase Rnf4 has been reported to act as a regulator of DNA repair, but the importance of RNF4 as a tumor suppressor has not been tested. Using a conditional-knockout mouse model, we deleted Rnf4 in the B cell lineage to test the importance of RNF4 for growth of somatic cells. Although Rnf4-conditional-knockout B cells exhibited substantial genomic instability, Rnf4 deletion caused no increase in tumor susceptibility. In contrast, Rnf4 deletion extended the healthy lifespan of mice expressing an oncogenic c-myc transgene. Rnf4 activity is essential for normal DNA replication, and in its absence, there was a failure in ATR-CHK1 signaling of replication stress. Factors that normally mediate replication fork stability, including members of the Fanconi anemia gene family and the helicases PIF1 and RECQL5, showed reduced accumulation at replication forks in the absence of RNF4. RNF4 deficiency also resulted in an accumulation of hyper-SUMOylated proteins in chromatin, including members of the SMC5/6 complex, which contributes to replication failure by a mechanism dependent on RAD51. These findings indicate that RNF4, which shows increased expression in multiple human tumor types, is a potential target for anticancer therapy, especially in tumors expressing c-myc.
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Affiliation(s)
- Joonyoung Her
- Department of Molecular Biology and Biochemistry and
| | - Haiyan Zheng
- Biological Mass Spectrometry Facility, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
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3
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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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4
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Xu MJ, Jordan PW. SMC5/6 Promotes Replication Fork Stability via Negative Regulation of the COP9 Signalosome. Int J Mol Sci 2024; 25:952. [PMID: 38256025 PMCID: PMC10815603 DOI: 10.3390/ijms25020952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 01/06/2024] [Accepted: 01/10/2024] [Indexed: 01/24/2024] Open
Abstract
It is widely accepted that DNA replication fork stalling is a common occurrence during cell proliferation, but there are robust mechanisms to alleviate this and ensure DNA replication is completed prior to chromosome segregation. The SMC5/6 complex has consistently been implicated in the maintenance of replication fork integrity. However, the essential role of the SMC5/6 complex during DNA replication in mammalian cells has not been elucidated. In this study, we investigate the molecular consequences of SMC5/6 loss at the replication fork in mouse embryonic stem cells (mESCs), employing the auxin-inducible degron (AID) system to deplete SMC5 acutely and reversibly in the defined cellular contexts of replication fork stall and restart. In SMC5-depleted cells, we identify a defect in the restart of stalled replication forks, underpinned by excess MRE11-mediated fork resection and a perturbed localization of fork protection factors to the stalled fork. Previously, we demonstrated a physical and functional interaction of SMC5/6 with the COP9 signalosome (CSN), a cullin deneddylase that enzymatically regulates cullin ring ligase (CRL) activity. Employing a combination of DNA fiber techniques, the AID system, small-molecule inhibition assays, and immunofluorescence microscopy analyses, we show that SMC5/6 promotes the localization of fork protection factors to stalled replication forks by negatively modulating the COP9 signalosome (CSN). We propose that the SMC5/6-mediated modulation of the CSN ensures that CRL activity and their roles in DNA replication fork stabilization are maintained to allow for efficient replication fork restart when a replication fork stall is alleviated.
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Affiliation(s)
- Michelle J. Xu
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Philip W. Jordan
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
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5
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Roy S, Zaker A, Mer A, D’Amours D. Large-scale phenogenomic analysis of human cancers uncovers frequent alterations affecting SMC5/6 complex components in breast cancer. NAR Cancer 2023; 5:zcad047. [PMID: 37705607 PMCID: PMC10495288 DOI: 10.1093/narcan/zcad047] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 08/09/2023] [Accepted: 08/22/2023] [Indexed: 09/15/2023] Open
Abstract
Cancer cells often experience large-scale alterations in genome architecture because of DNA damage and replication stress. Whether mutations in core regulators of chromosome structure can also lead to cancer-promoting loss in genome stability is not fully understood. To address this question, we conducted a systematic analysis of mutations affecting a global regulator of chromosome biology -the SMC5/6 complex- in cancer genomics cohorts. Analysis of 64 959 cancer samples spanning 144 tissue types and 199 different cancer genome studies revealed that the SMC5/6 complex is frequently altered in breast cancer patients. Patient-derived mutations targeting this complex associate with strong phenotypic outcomes such as loss of ploidy control and reduced overall survival. Remarkably, the phenotypic impact of several patient mutations can be observed in a heterozygous context, hence providing an explanation for a prominent role of SMC5/6 mutations in breast cancer pathogenesis. Overall, our findings suggest that genes encoding global effectors of chromosome architecture can act as key contributors to cancer development in humans.
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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
| | - Arvin Zaker
- Department of Biochemistry, Microbiology & Immunology, University of Ottawa, Roger Guindon Hall, 451 Smyth Rd, Ottawa, ON K1H 8M5, Canada
| | - Arvind Mer
- Department of Biochemistry, Microbiology & Immunology, 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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6
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Peng XP, Zhao X. The multi-functional Smc5/6 complex in genome protection and disease. Nat Struct Mol Biol 2023; 30:724-734. [PMID: 37336994 PMCID: PMC10372777 DOI: 10.1038/s41594-023-01015-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 05/05/2023] [Indexed: 06/21/2023]
Abstract
Structural maintenance of chromosomes (SMC) complexes are ubiquitous genome regulators with a wide range of functions. Among the three types of SMC complexes in eukaryotes, cohesin and condensin fold the genome into different domains and structures, while Smc5/6 plays direct roles in promoting chromosomal replication and repair and in restraining pathogenic viral extra-chromosomal DNA. The importance of Smc5/6 for growth, genotoxin resistance and host defense across species is highlighted by its involvement in disease prevention in plants and animals. Accelerated progress in recent years, including structural and single-molecule studies, has begun to provide greater insights into the mechanisms underlying Smc5/6 functions. Here we integrate a broad range of recent studies on Smc5/6 to identify emerging features of this unique SMC complex and to explain its diverse cellular functions and roles in disease pathogenesis. We also highlight many key areas requiring further investigation for achieving coherent views of Smc5/6-driven mechanisms.
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Affiliation(s)
- Xiao P Peng
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Xiaolan Zhao
- Molecular Biology Program, Sloan Kettering Cancer Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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7
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Ibars E, Codina-Fabra J, Bellí G, Casas C, Tarrés M, Solé-Soler R, Lorite NP, Ximénez-Embún P, Muñoz J, Colomina N, Torres-Rosell J. Ubiquitin proteomics identifies RNA polymerase I as a target of the Smc5/6 complex. Cell Rep 2023; 42:112463. [PMID: 37141096 DOI: 10.1016/j.celrep.2023.112463] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 12/29/2022] [Accepted: 04/18/2023] [Indexed: 05/05/2023] Open
Abstract
Ubiquitination controls numerous cellular processes, and its deregulation is associated with many pathologies. The Nse1 subunit in the Smc5/6 complex contains a RING domain with ubiquitin E3 ligase activity and essential functions in genome integrity. However, Nse1-dependent ubiquitin targets remain elusive. Here, we use label-free quantitative proteomics to analyze the nuclear ubiquitinome of nse1-C274A RING mutant cells. Our results show that Nse1 impacts the ubiquitination of several proteins involved in ribosome biogenesis and metabolism that, importantly, extend beyond canonical functions of Smc5/6. In addition, our analysis suggests a connection between Nse1 and RNA polymerase I (RNA Pol I) ubiquitination. Specifically, Nse1 and the Smc5/6 complex promote ubiquitination of K408 and K410 in the clamp domain of Rpa190, a modification that induces its degradation in response to blocks in transcriptional elongation. We propose that this mechanism contributes to Smc5/6-dependent segregation of the rDNA array, the locus transcribed by RNA Pol I.
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Affiliation(s)
- Eva Ibars
- Departament de Ciencies Mediques Basiques, Institut de Recerca Biomedica de Lleida, Universitat de Lleida, 25198 Lleida, Spain
| | - Joan Codina-Fabra
- Departament de Ciencies Mediques Basiques, Institut de Recerca Biomedica de Lleida, Universitat de Lleida, 25198 Lleida, Spain
| | - Gemma Bellí
- Departament de Ciencies Mediques Basiques, Institut de Recerca Biomedica de Lleida, Universitat de Lleida, 25198 Lleida, Spain
| | - Celia Casas
- Departament de Ciencies Mediques Basiques, Institut de Recerca Biomedica de Lleida, Universitat de Lleida, 25198 Lleida, Spain
| | - Marc Tarrés
- Departament de Ciencies Mediques Basiques, Institut de Recerca Biomedica de Lleida, Universitat de Lleida, 25198 Lleida, Spain
| | - Roger Solé-Soler
- Departament de Ciencies Mediques Basiques, Institut de Recerca Biomedica de Lleida, Universitat de Lleida, 25198 Lleida, Spain
| | - Neus P Lorite
- Departament de Ciencies Mediques Basiques, Institut de Recerca Biomedica de Lleida, Universitat de Lleida, 25198 Lleida, Spain
| | - Pilar Ximénez-Embún
- Proteomics Unit, Spanish National Cancer Research Center (CNIO), Madrid, Spain; ProteoRed-ISCIII, Madrid, Spain
| | - Javier Muñoz
- Proteomics Unit, Spanish National Cancer Research Center (CNIO), Madrid, Spain; ProteoRed-ISCIII, Madrid, Spain
| | - Neus Colomina
- Departament de Ciencies Mediques Basiques, Institut de Recerca Biomedica de Lleida, Universitat de Lleida, 25198 Lleida, Spain
| | - Jordi Torres-Rosell
- Departament de Ciencies Mediques Basiques, Institut de Recerca Biomedica de Lleida, Universitat de Lleida, 25198 Lleida, Spain.
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8
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González-Garrido C, Prado F. Parental histone distribution and location of the replication obstacle at nascent strands control homologous recombination. Cell Rep 2023; 42:112174. [PMID: 36862554 DOI: 10.1016/j.celrep.2023.112174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 12/09/2022] [Accepted: 02/10/2023] [Indexed: 03/03/2023] Open
Abstract
The advance and stability of replication forks rely on a tight co-regulation of DNA synthesis and nucleosome assembly. We show that mutants affected in parental histone recycling are impaired in the recombinational repair of the single-stranded DNA gaps generated in response to DNA adducts that hamper replication, which are then filled in by translesion synthesis. These recombination defects are in part due to an excess of parental nucleosomes at the invaded strand that destabilizes the sister chromatid junction formed after strand invasion through a Srs2-dependent mechanism. In addition, we show that a dCas9∗/R-loop is more recombinogenic when the dCas9∗/DNA-RNA hybrid interferes with the lagging than with the leading strand, and this recombination is particularly sensitive to problems in the deposition of parental histones at the strand that contains the hindrance. Therefore, parental histone distribution and location of the replication obstacle at the lagging or leading strand regulate homologous recombination.
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Affiliation(s)
- Cristina González-Garrido
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Universidad Pablo de Olavide, Seville, Spain
| | - Félix Prado
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Universidad Pablo de Olavide, Seville, Spain.
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9
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Stabilization of DNA fork junctions by Smc5/6 complexes revealed by single-molecule imaging. Cell Rep 2022; 41:111778. [PMID: 36476856 PMCID: PMC9756111 DOI: 10.1016/j.celrep.2022.111778] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 09/15/2022] [Accepted: 11/11/2022] [Indexed: 12/12/2022] Open
Abstract
SMC complexes play key roles in genome maintenance, where they ensure efficient genome replication and segregation. The SMC complex Smc5/6 is a crucial player in DNA replication and repair, yet many molecular features that determine its roles are unclear. Here, we use single-molecule microscopy to investigate Smc5/6's interaction with DNA. We find that Smc5/6 forms oligomers that dynamically redistribute on dsDNA by 1D diffusion and statically bind to ssDNA. Using combined force manipulation and single-molecule microscopy, we generate ssDNA-dsDNA junctions that mimic structures present in DNA repair intermediates or replication forks. We show that Smc5/6 accumulates at these junction sites, stabilizes the fork, and promotes the retention of RPA. Our observations provide a model for the complex's enrichment at sites of replication stress and DNA lesions from where it coordinates the recruitment and activation of downstream repair proteins.
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10
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Smc5/6 silences episomal transcription by a three-step function. Nat Struct Mol Biol 2022; 29:922-931. [PMID: 36097294 DOI: 10.1038/s41594-022-00829-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 07/29/2022] [Indexed: 11/08/2022]
Abstract
In addition to its role in chromosome maintenance, the six-membered Smc5/6 complex functions as a restriction factor that binds to and transcriptionally silences viral and other episomal DNA. However, the underlying mechanism is unknown. Here, we show that transcriptional silencing by the human Smc5/6 complex is a three-step process. The first step is entrapment of the episomal DNA by a mechanism dependent on Smc5/6 ATPase activity and a function of its Nse4a subunit for which the Nse4b paralog cannot substitute. The second step results in Smc5/6 recruitment to promyelocytic leukemia nuclear bodies by SLF2 (the human ortholog of Nse6). The third step promotes silencing through a mechanism requiring Nse2 but not its SUMO ligase activity. By contrast, the related cohesin and condensin complexes fail to bind to or silence episomal DNA, indicating a property unique to Smc5/6.
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11
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Hallett ST, Campbell Harry I, Schellenberger P, Zhou L, Cronin N, Baxter J, Etheridge T, Murray J, Oliver A. Cryo-EM structure of the Smc5/6 holo-complex. Nucleic Acids Res 2022; 50:9505-9520. [PMID: 35993814 PMCID: PMC9458440 DOI: 10.1093/nar/gkac692] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/14/2022] [Accepted: 07/30/2022] [Indexed: 01/06/2023] Open
Abstract
The Smc5/6 complex plays an essential role in the resolution of recombination intermediates formed during mitosis or meiosis, or as a result of the cellular response to replication stress. It also functions as a restriction factor preventing viral replication. Here, we report the cryogenic EM (cryo-EM) structure of the six-subunit budding yeast Smc5/6 holo-complex, reconstituted from recombinant proteins expressed in insect cells - providing both an architectural overview of the entire complex and an understanding of how the Nse1/3/4 subcomplex binds to the hetero-dimeric SMC protein core. In addition, we demonstrate that a region within the head domain of Smc5, equivalent to the 'W-loop' of Smc4 or 'F-loop' of Smc1, mediates an important interaction with Nse1. Notably, mutations that alter the surface-charge profile of the region of Nse1 which accepts the Smc5-loop, lead to a slow-growth phenotype and a global reduction in the chromatin-associated fraction of the Smc5/6 complex, as judged by single molecule localisation microscopy experiments in live yeast. Moreover, when taken together, our data indicates functional equivalence between the structurally unrelated KITE and HAWK accessory subunits associated with SMC complexes.
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Affiliation(s)
- Stephen T Hallett
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK
| | - Isabella Campbell Harry
- 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
| | - Nora B Cronin
- London Consortium for CryoEM (LonCEM) Facility, The Francis Crick Institute, London, UK
| | - Jonathan Baxter
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK
| | - Thomas J Etheridge
- Correspondence may also be addressed to Thomas J. Etheridge. Tel: +44 1273 678123;
| | - Johanne M Murray
- Correspondence may also be addressed to Johanne M. Murray. Tel: +44 1273 877191;
| | - Antony W Oliver
- To whom correspondence should be addressed. Tel: +44 1273 678349;
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12
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Gong X, Tian X, Xie H, Li Z. The structural maintenance of chromosomes 5 is a possible biomarker for individualized treatment of colorectal cancer. Cancer Med 2022; 12:3276-3287. [PMID: 35894836 PMCID: PMC9939147 DOI: 10.1002/cam4.5074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 06/16/2022] [Accepted: 07/03/2022] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Although the understanding of resistance to oxaliplatin (OXA) chemotherapy in colorectal cancer (CRC) has been sought for many years, drug tolerance remains a major challenge for cancer therapy. Revealing the molecular mechanism of OXA resistance could help to explain the poor prognosis of patients. METHODS Gene expression omnibus (GEO) database was searched, GSE83129, which contains RNA profiling in metastatic CRC patients treated first-line with OXA, was chosen for the following analysis. Differential expressed genes (DEGs) between the adenocarcinoma and adjacent_normal team, respectively, in the OXA responders and no-responders were analyzed. The Gene Ontology (GO) and hub genes in the protein-protein interaction (PPI) network were used for the molecular mechanism of OXA resistance. Tumor-related databases were used for the clinical relevance of the structural maintenance of chromosomes 5 (SMC5) in CRC. The in vitro assays were used to detect the molecular function of SMC5 in CRC cells. Quantitative real-time PCR (qRT-PCR) and western blot were used to detect the expression of the structural maintenance of chromosomes 5/6 (SMC5/6) complex components upon OXA and raltitrexed (RTX) treatment. CCK-8 was used to detect the cell viability of cells with different treatment. RESULTS SMC5 was downregulated in CRC tissues of OXA no-response patients. Lower expression of SMC5 was correlated with a poor prognosis in CRC patients, improved this gene expression, inhibited the CRC cell growth and invasion in vitro. Furthermore, SMC5 was downregulated upon OXA treatment in CRC cells, while RTX would reverse its expression, and the combination of these two drugs restored the SMC5 level to the normal situation. Finally, RTX treatment enhanced the OXA cytotoxicity. CONCLUSION SMC5 is a tumor suppressor, that low expression of this gene is benefit for the development of CRC. Combination treatment with RTX and OXA may be more suitable for those OXA no-responders with lower SMC5.
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Affiliation(s)
- Xiaoxia Gong
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human DiseasesSoutheast UniversityNanjingChina
| | - Xiaowei Tian
- General Surgery DepartmentQingdao Municipal Hospital affiliated to Qingdao UniversityQingdaoChina
| | - Hao Xie
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human DiseasesSoutheast UniversityNanjingChina
| | - Zhaoshui Li
- Qingdao Medical CollegeQingdao UniversityQingdaoChina
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13
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Varejão N, Lascorz J, Codina-Fabra J, Bellí G, Borràs-Gas H, Torres-Rosell J, Reverter D. Structural basis for the E3 ligase activity enhancement of yeast Nse2 by SUMO-interacting motifs. Nat Commun 2021; 12:7013. [PMID: 34853311 PMCID: PMC8636563 DOI: 10.1038/s41467-021-27301-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 11/09/2021] [Indexed: 01/02/2023] Open
Abstract
Post-translational modification of proteins by ubiquitin and ubiquitin-like modifiers, such as SUMO, are key events in protein homeostasis or DNA damage response. Smc5/6 is a nuclear multi-subunit complex that participates in the recombinational DNA repair processes and is required in the maintenance of chromosome integrity. Nse2 is a subunit of the Smc5/6 complex that possesses SUMO E3 ligase activity by the presence of a SP-RING domain that activates the E2~SUMO thioester for discharge on the substrate. Here we present the crystal structure of the SUMO E3 ligase Nse2 in complex with an E2-SUMO thioester mimetic. In addition to the interface between the SP-RING domain and the E2, the complex reveals how two SIM (SUMO-Interacting Motif) -like motifs in Nse2 are restructured upon binding the donor and E2-backside SUMO during the E3-dependent discharge reaction. Both SIM interfaces are essential in the activity of Nse2 and are required to cope with DNA damage. Nse2 is a SUMO E3 ligase component of the Smc5/6 multisubunit complex involved in the DNA repair and chromosome integrity. Here, the structure of the Nse2 in complex with an E2-SUMO thioester mimetic reveals the combined action of two SIM motifs during the E3- dependent conjugation reaction.
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Affiliation(s)
- Nathalia Varejão
- Institut de Biotecnologia i de Biomedicina (IBB) and Dept. de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - Jara Lascorz
- Institut de Biotecnologia i de Biomedicina (IBB) and Dept. de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - Joan Codina-Fabra
- IRBLLEIDA, Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - Gemma Bellí
- IRBLLEIDA, Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - Helena Borràs-Gas
- Institut de Biotecnologia i de Biomedicina (IBB) and Dept. de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - Jordi Torres-Rosell
- IRBLLEIDA, Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, Lleida, Spain
| | - David Reverter
- Institut de Biotecnologia i de Biomedicina (IBB) and Dept. de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain.
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14
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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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Bradley AI, Marsh NM, Borror HR, Mostoller KE, Gama AI, Gardner RG. Acute ethanol stress induces sumoylation of conserved chromatin structural proteins in Saccharomyces cerevisiae. Mol Biol Cell 2021; 32:1121-1133. [PMID: 33788582 PMCID: PMC8351541 DOI: 10.1091/mbc.e20-11-0715] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Stress is ubiquitous to life and can irreparably damage essential biomolecules and organelles in cells. To survive, organisms must sense and adapt to stressful conditions. One highly conserved adaptive stress response is through the posttranslational modification of proteins by the small ubiquitin-like modifier (SUMO). Here, we examine the effects of acute ethanol stress on protein sumoylation in the budding yeast Saccharomyces cerevisiae. We found that cells exhibit a transient sumoylation response after acute exposure to ≤7.5% vol/vol ethanol. By contrast, the sumoylation response becomes chronic at 10% ethanol exposure. Mass spectrometry analyses identified 18 proteins that are sumoylated after acute ethanol exposure, with 15 known to associate with chromatin. Upon further analysis, we found that the chromatin structural proteins Smc5 and Smc6 undergo ethanol-induced sumoylation that depends on the activity of the E3 SUMO ligase Mms21. Using cell-cycle arrest assays, we observed that Smc5 and Smc6 ethanol-induced sumoylation occurs during G1 and G2/M phases but not S phase. Acute ethanol exposure also resulted in the formation of Rad52 foci at levels comparable to Rad52 foci formation after exposure to the DNA alkylating agent methyl methanesulfonate (MMS). MMS exposure is known to induce the intra-S-phase DNA damage checkpoint via Rad53 phosphorylation, but ethanol exposure did not induce Rad53 phosphorylation. Ethanol abrogated the effect of MMS on Rad53 phosphorylation when added simultaneously. From these studies, we propose that acute ethanol exposure induces a change in chromatin leading to sumoylation of specific chromatin structural proteins.
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Affiliation(s)
- Amanda I Bradley
- Department of Pharmacology, University of Washington, Seattle, WA 98195.,Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195
| | - Nicole M Marsh
- Department of Pharmacology, University of Washington, Seattle, WA 98195
| | - Heather R Borror
- Department of Pharmacology, University of Washington, Seattle, WA 98195
| | | | - Amber I Gama
- Department of Pharmacology, University of Washington, Seattle, WA 98195
| | - Richard G Gardner
- Department of Pharmacology, University of Washington, Seattle, WA 98195.,Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195
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C-Terminal HA Tags Compromise Function and Exacerbate Phenotypes of Saccharomyces cerevisiae Bloom's Helicase Homolog Sgs1 SUMOylation-Associated Mutants. G3-GENES GENOMES GENETICS 2020; 10:2811-2818. [PMID: 32540865 PMCID: PMC7407464 DOI: 10.1534/g3.120.401324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The Sgs1 helicase and Top3-Rmi1 decatenase form a complex that affects homologous recombination outcomes during the mitotic cell cycle and during meiosis. Previous studies have reported that Sgs1-Top3-Rmi1 function is regulated by SUMOylation that is catalyzed by the Smc5-Smc6-Mms21 complex. These studies used strains in which SGS1 was C-terminally tagged with three or six copies of a human influenza hemagglutinin-derived epitope tag (3HA and 6HA). They identified SGS1 mutants that affect its SUMOylation, which we will refer to as SGS1 SUMO-site mutants. In previous work, these mutants showed phenotypes consistent with substantial loss of Sgs1-Top3-Rmi1 function during the mitotic cell cycle. We find that the reported phenotypes are largely due to the presence of the HA epitope tags. Untagged SGS1 SUMO-site mutants show either wild-type or weak hypomorphic phenotypes, depending on the assay. These phenotypes are exacerbated by both 6HA and 3HA epitope tags in two different S. cerevisiae strain backgrounds. Importantly, a C-terminal 6HA tag confers strong hypomorphic or null phenotypes on an otherwise wild-type Sgs1 protein. Taken together, these results suggest that the HA epitope tags used in previous studies seriously compromise Sgs1 function. Furthermore, they raise the possibilities either that sufficient SUMOylation of the Sgs1-Top3-Rmi1 complex might still occur in the SUMO-site mutants isolated, or that Smc5-Smc6-Mms21-mediated SUMOylation plays a minor role in the regulation of Sgs1-Top3-Rmi1 during recombination.
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