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Audry J, Zhang H, Kerr C, Berkner KL, Runge K. Ccq1 restrains Mre11-mediated degradation to distinguish short telomeres from double-strand breaks. Nucleic Acids Res 2024; 52:3722-3739. [PMID: 38321948 PMCID: PMC11040153 DOI: 10.1093/nar/gkae044] [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: 05/25/2023] [Revised: 12/21/2023] [Accepted: 01/12/2024] [Indexed: 02/08/2024] Open
Abstract
Telomeres protect chromosome ends and are distinguished from DNA double-strand breaks (DSBs) by means of a specialized chromatin composed of DNA repeats bound by a multiprotein complex called shelterin. We investigated the role of telomere-associated proteins in establishing end-protection by studying viable mutants lacking these proteins. Mutants were studied using a Schizosaccharomyces pombe model system that induces cutting of a 'proto-telomere' bearing telomere repeats to rapidly form a new stable chromosomal end, in contrast to the rapid degradation of a control DSB. Cells lacking the telomere-associated proteins Taz1, Rap1, Poz1 or Rif1 formed a chromosome end that was stable. Surprisingly, cells lacking Ccq1, or impaired for recruiting Ccq1 to the telomere, converted the cleaved proto-telomere to a rapidly degraded DSB. Ccq1 recruits telomerase, establishes heterochromatin and affects DNA damage checkpoint activation; however, these functions were separable from protection of the new telomere by Ccq1. In cells lacking Ccq1, telomere degradation was greatly reduced by eliminating the nuclease activity of Mre11 (part of the Mre11-Rad50-Nbs1/Xrs2 DSB processing complex), and higher amounts of nuclease-deficient Mre11 associated with the new telomere. These results demonstrate a novel function for S. pombe Ccq1 to effect end-protection by restraining Mre11-dependent degradation of the DNA end.
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Affiliation(s)
- Julien Audry
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Haitao Zhang
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Carly Kerr
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Kathleen L Berkner
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Kurt W Runge
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
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2
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Sun H, Wu Z, Zhou Y, Lu Y, Lu H, Chen H, Shi S, Zeng Z, Wu J, Lei M. Structural insights into Pot1-ssDNA, Pot1-Tpz1 and Tpz1-Ccq1 Interactions within fission yeast shelterin complex. PLoS Genet 2022; 18:e1010308. [PMID: 35849625 PMCID: PMC9333443 DOI: 10.1371/journal.pgen.1010308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 07/28/2022] [Accepted: 06/22/2022] [Indexed: 11/30/2022] Open
Abstract
The conserved shelterin complex caps chromosome ends to protect telomeres and regulate telomere replication. In fission yeast Schizosaccharomyces pombe, shelterin consists of telomeric single- and double-stranded DNA-binding modules Pot1-Tpz1 and Taz1-Rap1 connected by Poz1, and a specific component Ccq1. While individual structures of the two DNA-binding OB folds of Pot1 (Pot1OB1-GGTTAC and Pot1OB2-GGTTACGGT) are available, structural insight into recognition of telomeric repeats with spacers by the complete DNA-binding domain (Pot1DBD) remains an open question. Moreover, structural information about the Tpz1-Ccq1 interaction requires to be revealed for understanding how the specific component Ccq1 of S. pombe shelterin is recruited to telomeres to function as an interacting hub. Here, we report the crystal structures of Pot1DBD-single-stranded-DNA, Pot1372-555-Tpz1185-212 and Tpz1425-470-Ccq1123-439 complexes and propose an integrated model depicting the assembly mechanism of the shelterin complex at telomeres. The structure of Pot1DBD-DNA unveils how Pot1 recognizes S. pombe degenerate telomeric sequences. Our analyses of Tpz1-Ccq1 reveal structural basis for the essential role of the Tpz1-Ccq1 interaction in telomere recruitment of Ccq1 that is required for telomere maintenance and telomeric heterochromatin formation. Overall, our findings provide valuable structural information regarding interactions within fission yeast shelterin complex at 3’ ss telomeric overhang. Telomeres, composed of repetitive DNA sequences and specialized proteins, are protective structures at the ends of linear chromosomes. The telomere structure is essential for the maintenance of genome integrity and stability, and telomere dysfunction has been linked to human development, aging, cancer and a variety of degenerative diseases. An evolutionarily conserved multiple-protein complex called shelterin plays versatile roles in telomere homeostasis regulation, end protection and heterochromatin establishment. However, the highly flexible nature of shelterin complex has greatly impeded our structural and functional understanding for this important complex. In fission yeast, structures of the shelterin dsDNA-binding protein subcomplex Taz1-Rap1 and the bridge subcomplex Tpz1-Poz1-Rap1 are available. Although individual OB-fold subdomains structures have been characterized, structural information about the complete Pot1DBD bound to telomeric repeats with spacers remains to be revealed. Here, by determining the crystal structures of the telomeric overhang binding Pot1DBD-ssDNA, Pot1372-555-Tpz1185-212 and Tpz1425-470-Ccq1123-439 subcomplexes, we provide structural basis not only for the recognition of S. pombe degenerate telomeric sequences by Pot1, but also for the essential function of the Tpz1-Ccq1 interaction in Ccq1 recruitment to telomeres for telomere maintenance and telomeric heterochromatin formation. These findings provide an integrated model depicting the assembly mechanism of the shelterin complex at telomeres and its multiple roles in telomere biology.
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Affiliation(s)
- Hong Sun
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Zhenfang Wu
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Institute of Precision Medicine, Shanghai, China
- * E-mail: (ZW); (ZZ); (JW); (ML)
| | - Yuanze Zhou
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Yanjia Lu
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Institute of Precision Medicine, Shanghai, China
| | - Huaisheng Lu
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Institute of Precision Medicine, Shanghai, China
| | - Hongwen Chen
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Shaohua Shi
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Institute of Precision Medicine, Shanghai, China
| | - Zhixiong Zeng
- Shandong Provincial Key Laboratory of Microbial Engineering, College of Bioengineering, Qilu University of Technology, Shandong, China
- * E-mail: (ZW); (ZZ); (JW); (ML)
| | - Jian Wu
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Institute of Precision Medicine, Shanghai, China
- * E-mail: (ZW); (ZZ); (JW); (ML)
| | - Ming Lei
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Institute of Precision Medicine, Shanghai, China
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail: (ZW); (ZZ); (JW); (ML)
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3
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Subtelomeric Chromatin in the Fission Yeast S. pombe. Microorganisms 2021; 9:microorganisms9091977. [PMID: 34576871 PMCID: PMC8466458 DOI: 10.3390/microorganisms9091977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/06/2021] [Accepted: 09/14/2021] [Indexed: 01/15/2023] Open
Abstract
Telomeres play important roles in safeguarding the genome. The specialized repressive chromatin that assembles at telomeres and subtelomeric domains is key to this protective role. However, in many organisms, the repetitive nature of telomeric and subtelomeric sequences has hindered research efforts. The fission yeast S. pombe has provided an important model system for dissection of chromatin biology due to the relative ease of genetic manipulation and strong conservation of important regulatory proteins with higher eukaryotes. Telomeres and the telomere-binding shelterin complex are highly conserved with mammals, as is the assembly of constitutive heterochromatin at subtelomeres. In this review, we seek to summarize recent work detailing the assembly of distinct chromatin structures within subtelomeric domains in fission yeast. These include the heterochromatic SH subtelomeric domains, the telomere-associated sequences (TAS), and ST chromatin domains that assemble highly condensed chromatin clusters called knobs. Specifically, we review new insights into the sequence of subtelomeric domains, the distinct types of chromatin that assemble on these sequences and how histone H3 K36 modifications influence these chromatin structures. We address the interplay between the subdomains of chromatin structure and how subtelomeric chromatin is influenced by both the telomere-bound shelterin complexes and by euchromatic chromatin regulators internal to the subtelomeric domain. Finally, we demonstrate that telomere clustering, which is mediated via the condensed ST chromatin knob domains, does not depend on knob assembly within these domains but on Set2, which mediates H3K36 methylation.
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Shi S, Zhou Y, Lu Y, Sun H, Xue J, Wu Z, Lei M. Ccq1-Raf2 interaction mediates CLRC recruitment to establish heterochromatin at telomeres. Life Sci Alliance 2021; 4:4/11/e202101106. [PMID: 34493579 PMCID: PMC8424379 DOI: 10.26508/lsa.202101106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 12/01/2022] Open
Abstract
This study unveils a role of Ccq1–Raf2 interaction in CLRC recruitment to establish heterochromatin at telomeres, providing a positive feedback mechanism between shelterin and CLRC for subtelomeric heterochromatin assembly. Telomeres, highly ordered DNA-protein complexes at eukaryotic linear chromosome ends, are specialized heterochromatin loci conserved among eukaryotes. In Schizosaccharomyces pombe, the shelterin complex is important for subtelomeric heterochromatin establishment. Despite shelterin has been demonstrated to mediate the recruitment of the Snf2/histone deacetylase–containing repressor complex (SHREC) and the Clr4 methyltransferase complex (CLRC) to telomeres, the mechanism involved in telomeric heterochromatin assembly remains elusive due to the multiple functions of the shelterin complex. Here, we found that CLRC plays a dominant role in heterochromatin establishment at telomeres. In addition, we identified a series of amino acids in the shelterin subunit Ccq1 that are important for the specific interaction between Ccq1 and the CLRC subunit Raf2. Finally, we demonstrated that the Ccq1–Raf2 interaction is essential for the recruitment of CLRC to telomeres, that contributes to histone H3 lysine 9 methylation, nucleosome stability and the shelterin-chromatin association, promoting a positive feedback mechanism for the nucleation and spreading of heterochromatin at subtelomeres. Together, our findings provide a mechanistic understanding of subtelomeric heterochromatin assembly by shelterin-dependent CLRC recruitment to chromosomal ends.
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Affiliation(s)
- Shaohua Shi
- State Key Laboratory of Oncogenes and Related Genes, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Institute of Precision Medicine, Shanghai, China
| | - Yuanze Zhou
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Yanjia Lu
- State Key Laboratory of Oncogenes and Related Genes, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Institute of Precision Medicine, Shanghai, China
| | - Hong Sun
- State Key Laboratory of Molecular Biology, Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Jing Xue
- State Key Laboratory of Molecular Biology, Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Zhenfang Wu
- State Key Laboratory of Oncogenes and Related Genes, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China .,Shanghai Institute of Precision Medicine, Shanghai, China
| | - Ming Lei
- State Key Laboratory of Oncogenes and Related Genes, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China .,Shanghai Institute of Precision Medicine, Shanghai, China.,Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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5
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Liu J, Hu X, Bao K, Kim JK, Zhang C, Jia S, Qiao F. The cooperative assembly of shelterin bridge provides a kinetic gateway that controls telomere length homeostasis. Nucleic Acids Res 2021; 49:8110-8119. [PMID: 34255844 PMCID: PMC8373121 DOI: 10.1093/nar/gkab550] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 06/08/2021] [Accepted: 06/13/2021] [Indexed: 11/14/2022] Open
Abstract
Shelterin is a six-protein complex that coats chromosome ends to ensure their proper protection and maintenance. Similar to the human shelterin, fission yeast shelterin is composed of telomeric double- and single-stranded DNA-binding proteins, Taz1 and Pot1, respectively, bridged by Rap1, Poz1 and Tpz1. The assembly of the proteinaceous Tpz1-Poz1-Rap1 complex occurs cooperatively and disruption of this shelterin bridge leads to unregulated telomere elongation. However, how this biophysical property of bridge assembly is integrated into shelterin function is not known. Here, utilizing synthetic bridges with a range of binding properties, we find that synthetic shelterin bridge lacking cooperativity requires a linker pair that matches the native bridge in complex lifespan but has dramatically higher affinity. We find that cooperative assembly confers kinetic properties on the shelterin bridge allowing disassembly to function as a molecular timer, regulating the duration of the telomere open state, and consequently telomere lengthening to achieve a defined species-specific length range.
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Affiliation(s)
- Jinqiang Liu
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA
| | - Xichan Hu
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA
| | - Kehan Bao
- Department of Biological Sciences, Columbia University, New York City, NY 92697-4560, USA
| | - Jin-Kwang Kim
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA
| | - Catherine Zhang
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York City, NY 92697-4560, USA
| | - Feng Qiao
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA
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Roisné-Hamelin F, Pobiega S, Jézéquel K, Miron S, Dépagne J, Veaute X, Busso D, Du MHL, Callebaut I, Charbonnier JB, Cuniasse P, Zinn-Justin S, Marcand S. Mechanism of MRX inhibition by Rif2 at telomeres. Nat Commun 2021; 12:2763. [PMID: 33980827 PMCID: PMC8115599 DOI: 10.1038/s41467-021-23035-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 04/13/2021] [Indexed: 02/06/2023] Open
Abstract
Specific proteins present at telomeres ensure chromosome end stability, in large part through unknown mechanisms. In this work, we address how the Saccharomyces cerevisiae ORC-related Rif2 protein protects telomere. We show that the small N-terminal Rif2 BAT motif (Blocks Addition of Telomeres) previously known to limit telomere elongation and Tel1 activity is also sufficient to block NHEJ and 5' end resection. The BAT motif inhibits the ability of the Mre11-Rad50-Xrs2 complex (MRX) to capture DNA ends. It acts through a direct contact with Rad50 ATP-binding Head domains. Through genetic approaches guided by structural predictions, we identify residues at the surface of Rad50 that are essential for the interaction with Rif2 and its inhibition. Finally, a docking model predicts how BAT binding could specifically destabilise the DNA-bound state of the MRX complex. From these results, we propose that when an MRX complex approaches a telomere, the Rif2 BAT motif binds MRX Head in its ATP-bound resting state. This antagonises MRX transition to its DNA-bound state, and favours a rapid return to the ATP-bound state. Unable to stably capture the telomere end, the MRX complex cannot proceed with the subsequent steps of NHEJ, Tel1-activation and 5' resection.
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Affiliation(s)
- Florian Roisné-Hamelin
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Sabrina Pobiega
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Kévin Jézéquel
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Simona Miron
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Jordane Dépagne
- CIGEx, Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Xavier Veaute
- CIGEx, Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Didier Busso
- CIGEx, Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Marie-Hélène Le Du
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Isabelle Callebaut
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie de Physique des Matériaux et de Cosmochimie (IMPMC), Paris, France
| | - Jean-Baptiste Charbonnier
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Philippe Cuniasse
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Sophie Zinn-Justin
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Stéphane Marcand
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France.
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7
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Fernandes CAH, Morea EGO, Dos Santos GA, da Silva VL, Vieira MR, Viviescas MA, Chatain J, Vadel A, Saintomé C, Fontes MRM, Cano MIN. A multi-approach analysis highlights the relevance of RPA-1 as a telomere end-binding protein (TEBP) in Leishmania amazonensis. Biochim Biophys Acta Gen Subj 2020; 1864:129607. [PMID: 32222548 DOI: 10.1016/j.bbagen.2020.129607] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 02/21/2020] [Accepted: 03/24/2020] [Indexed: 01/12/2023]
Abstract
BACKGROUND Telomeres are chromosome end structures important in the maintenance of genome homeostasis. They are replenished by the action of telomerase and associated proteins, such as the OB (oligonucleotide/oligosaccharide-binding)-fold containing telomere-end binding proteins (TEBP) which plays an essential role in telomere maintenance and protection. The nature of TEBPs is well known in higher and some primitive eukaryotes, but it remains undetermined in trypanosomatids. Previous in silico searches have shown that there are no homologs of the classical TEPBs in trypanosomatids, including Leishmania sp. However, Replication Protein A subunit 1 (RPA-1), an OB-fold containing DNA-binding protein, was found co-localized with trypanosomatids telomeres and showed a high preference for the telomeric G-rich strand. METHODS AND RESULTS We predicted the absence of structural homologs of OB-fold containing TEBPs in the Leishmania sp. genome using structural comparisons. We demonstrated by molecular docking that the ssDNA binding mode of LaRPA-1 shares features with the higher eukaryotes POT1 and RPA-1 crystal structures ssDNA binding mode. Using fluorescence spectroscopy, protein-DNA interaction assays, and FRET, we respectively show that LaRPA-1 shares some telomeric functions with the classical TEBPs since it can bind at least one telomeric repeat, protect the telomeric G-rich DNA from 3'-5' Exonuclease I digestion, and unfold telomeric G-quadruplex. CONCLUSIONS Our results suggest that RPA-1 emerges as a TEBP in trypanosomatids, and in this context, we present two possible evolutionary landscapes of trypanosomatids RPA-1 that could reflect upon the evolution of OB-fold containing TEBPs from all eukaryotes.
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Affiliation(s)
- Carlos A H Fernandes
- Department of Biophysics and Pharmacology, Biosciences Institute, São Paulo State University (UNESP) - Botucatu, SP, Brazil; Laboratoire de Biologie et Pharmacologie Appliquée, École Normale Supérieure Paris-Saclay, Cachan, France
| | - Edna Gicela O Morea
- Department of Chemical and Biological Sciences, São Paulo State University (UNESP) - Botucatu, SP, Brazil
| | - Gabriel A Dos Santos
- Department of Chemical and Biological Sciences, São Paulo State University (UNESP) - Botucatu, SP, Brazil
| | - Vitor L da Silva
- Department of Chemical and Biological Sciences, São Paulo State University (UNESP) - Botucatu, SP, Brazil
| | - Marina Roveri Vieira
- Department of Chemical and Biological Sciences, São Paulo State University (UNESP) - Botucatu, SP, Brazil
| | - Maria Alejandra Viviescas
- Department of Chemical and Biological Sciences, São Paulo State University (UNESP) - Botucatu, SP, Brazil
| | - Jean Chatain
- MNHN CNRS UMR 7196, INSERM U1154, 43 rue Cuvier, 75005 Paris, France
| | - Aurélie Vadel
- MNHN CNRS UMR 7196, INSERM U1154, 43 rue Cuvier, 75005 Paris, France
| | - Carole Saintomé
- MNHN CNRS UMR 7196, INSERM U1154, 43 rue Cuvier, 75005 Paris, France; Sorbonne Université, UFR927, 4 place Jussieu, 75005 Paris, France
| | - Marcos Roberto M Fontes
- Department of Biophysics and Pharmacology, Biosciences Institute, São Paulo State University (UNESP) - Botucatu, SP, Brazil
| | - Maria Isabel Nogueira Cano
- Department of Chemical and Biological Sciences, São Paulo State University (UNESP) - Botucatu, SP, Brazil.
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8
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Hu Y, Bennett HW, Liu N, Moravec M, Williams JF, Azzalin CM, King MC. RNA-DNA Hybrids Support Recombination-Based Telomere Maintenance in Fission Yeast. Genetics 2019; 213:431-447. [PMID: 31405990 PMCID: PMC6781888 DOI: 10.1534/genetics.119.302606] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 08/09/2019] [Indexed: 11/18/2022] Open
Abstract
A subset of cancers rely on telomerase-independent mechanisms to maintain their chromosome ends. The predominant "alternative lengthening of telomeres" pathway appears dependent on homology-directed repair (HDR) to maintain telomeric DNA. However, the molecular changes needed for cells to productively engage in telomeric HDR are poorly understood. To gain new insights into this transition, we monitored the state of telomeres during serial culture of fission yeast (Schizosaccharomyces pombe) lacking the telomerase recruitment factor Ccq1. Rad52 is loaded onto critically short telomeres shortly after germination despite continued telomere erosion, suggesting that recruitment of recombination factors is not sufficient to maintain telomeres in the absence of telomerase function. Instead, survivor formation coincides with the derepression of telomeric repeat-containing RNA (TERRA). In this context, degradation of TERRA associated with the telomere in the form of R-loops drives a severe growth crisis, ultimately leading to a novel type of survivor with linear chromosomes and altered cytological telomere characteristics, including the loss of the shelterin component Rap1 (but not the TRF1/TRF2 ortholog, Taz1) from the telomere. We demonstrate that deletion of Rap1 is protective in this context, preventing the growth crisis that is otherwise triggered by degradation of telomeric R-loops in survivors with linear chromosomes. These findings suggest that upregulation of telomere-engaged TERRA, or altered recruitment of shelterin components, can support telomerase-independent telomere maintenance.
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Affiliation(s)
- Yan Hu
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520-8002
| | - Henrietta W Bennett
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520-8002
| | - Na Liu
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520-8002
| | - Martin Moravec
- Institute of Biochemistry (IBC), Eidgenössische Technische Hochschule Zürich (ETHZ), 8093, Switzerland
| | - Jessica F Williams
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520-8002
| | - Claus M Azzalin
- Instituto de Medicina Molecular João Lobo Antunes (iMM), Faculdade de Medicina da Universidade de Lisboa, 1649-028, Portugal
| | - Megan C King
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520-8002
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9
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TASks for subtelomeres: when nucleosome loss and genome instability are favored. Curr Genet 2019; 65:1153-1160. [DOI: 10.1007/s00294-019-00986-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 04/29/2019] [Accepted: 04/30/2019] [Indexed: 10/26/2022]
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10
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van Emden TS, Forn M, Forné I, Sarkadi Z, Capella M, Martín Caballero L, Fischer-Burkart S, Brönner C, Simonetta M, Toczyski D, Halic M, Imhof A, Braun S. Shelterin and subtelomeric DNA sequences control nucleosome maintenance and genome stability. EMBO Rep 2018; 20:embr.201847181. [PMID: 30420521 DOI: 10.15252/embr.201847181] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 10/03/2018] [Accepted: 10/12/2018] [Indexed: 11/09/2022] Open
Abstract
Telomeres and the shelterin complex cap and protect the ends of chromosomes. Telomeres are flanked by the subtelomeric sequences that have also been implicated in telomere regulation, although their role is not well defined. Here, we show that, in Schizosaccharomyces pombe, the telomere-associated sequences (TAS) present on most subtelomeres are hyper-recombinogenic, have metastable nucleosomes, and unusual low levels of H3K9 methylation. Ccq1, a subunit of shelterin, protects TAS from nucleosome loss by recruiting the heterochromatic repressor complexes CLRC and SHREC, thereby linking nucleosome stability to gene silencing. Nucleosome instability at TAS is independent of telomeric repeats and can be transmitted to an intrachromosomal locus containing an ectopic TAS fragment, indicating that this is an intrinsic property of the underlying DNA sequence. When telomerase recruitment is compromised in cells lacking Ccq1, DNA sequences present in the TAS promote recombination between chromosomal ends, independent of nucleosome abundance, implying an active function of these sequences in telomere maintenance. We propose that Ccq1 and fragile subtelomeres co-evolved to regulate telomere plasticity by controlling nucleosome occupancy and genome stability.
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Affiliation(s)
- Thomas S van Emden
- Department of Physiological Chemistry, BioMedical Center (BMC), Ludwig Maximilians University of Munich, Martinsried, Germany.,International Max Planck Research School for Molecular and Cellular Life Sciences, Martinsried, Germany
| | - Marta Forn
- Department of Physiological Chemistry, BioMedical Center (BMC), Ludwig Maximilians University of Munich, Martinsried, Germany
| | - Ignasi Forné
- Protein Analysis Unit (ZfP), BioMedical Center (BMC), Ludwig Maximilians University of Munich, Martinsried, Germany
| | - Zsuzsa Sarkadi
- Department of Physiological Chemistry, BioMedical Center (BMC), Ludwig Maximilians University of Munich, Martinsried, Germany
| | - Matías Capella
- Department of Physiological Chemistry, BioMedical Center (BMC), Ludwig Maximilians University of Munich, Martinsried, Germany
| | - Lucía Martín Caballero
- Department of Physiological Chemistry, BioMedical Center (BMC), Ludwig Maximilians University of Munich, Martinsried, Germany.,International Max Planck Research School for Molecular and Cellular Life Sciences, Martinsried, Germany
| | - Sabine Fischer-Burkart
- Department of Physiological Chemistry, BioMedical Center (BMC), Ludwig Maximilians University of Munich, Martinsried, Germany
| | - Cornelia Brönner
- Department of Biochemistry, Gene Center, Ludwig Maximilians University of Munich, Munich, Germany
| | - Marco Simonetta
- Department of Biophysics and Biochemistry, University of California San Francisco (UCSF), San Francisco, CA, USA
| | - David Toczyski
- Department of Biophysics and Biochemistry, University of California San Francisco (UCSF), San Francisco, CA, USA
| | - Mario Halic
- Department of Biochemistry, Gene Center, Ludwig Maximilians University of Munich, Munich, Germany
| | - Axel Imhof
- Protein Analysis Unit (ZfP), BioMedical Center (BMC), Ludwig Maximilians University of Munich, Martinsried, Germany
| | - Sigurd Braun
- Department of Physiological Chemistry, BioMedical Center (BMC), Ludwig Maximilians University of Munich, Martinsried, Germany .,International Max Planck Research School for Molecular and Cellular Life Sciences, Martinsried, Germany
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How long does telomerase extend telomeres? Regulation of telomerase release and telomere length homeostasis. Curr Genet 2018; 64:1177-1181. [PMID: 29663033 PMCID: PMC6223848 DOI: 10.1007/s00294-018-0836-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 04/09/2018] [Accepted: 04/09/2018] [Indexed: 01/28/2023]
Abstract
Telomerase, the enzyme that replenishes telomeres, is essential for most eukaryotes to maintain their generations. Telomere length homeostasis is achieved via a balance between telomere lengthening by telomerase, and erosion over successive cell divisions. Impaired telomerase regulation leads to shortened telomeres and can cause defects in tissue maintenance. Telomeric DNA is composed of a repetitive sequence, which recruits the protective protein complex, shelterin. Shelterin, together with chromatin remodelling proteins, shapes the heterochromatic structure at the telomere and protects chromosome ends. Shelterin also provides a foothold for telomerase to be recruited and facilitates telomere extension. Such mechanisms of telomere recruitment and activation are conserved from unicellular eukaryotes to humans, with the rate of telomere extension playing an important role in determining the length maintained. Telomerase can be processive, adding multiple telomeric repeats before dissociating. However, a question remains: how does telomerase determine the number of repeats to add? In this review, I will discuss about how telomerase can monitor telomere extension using fission yeast as a model. I propose a model whereby the accumulation of the Pot1 complex on the synthesised telomere single-strand counteracts retention of telomerase via chromatin proteins and the similar system may be conserved in mammals.
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