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Kuse R, Ishii K. Flexible Attachment and Detachment of Centromeres and Telomeres to and from Chromosomes. Biomolecules 2023; 13:1016. [PMID: 37371596 DOI: 10.3390/biom13061016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/15/2023] [Accepted: 06/18/2023] [Indexed: 06/29/2023] Open
Abstract
Accurate transmission of genomic information across multiple cell divisions and generations, without any losses or errors, is fundamental to all living organisms. To achieve this goal, eukaryotes devised chromosomes. Eukaryotic genomes are represented by multiple linear chromosomes in the nucleus, each carrying a centromere in the middle, a telomere at both ends, and multiple origins of replication along the chromosome arms. Although all three of these DNA elements are indispensable for chromosome function, centromeres and telomeres possess the potential to detach from the original chromosome and attach to new chromosomal positions, as evident from the events of telomere fusion, centromere inactivation, telomere healing, and neocentromere formation. These events seem to occur spontaneously in nature but have not yet been elucidated clearly, because they are relatively infrequent and sometimes detrimental. To address this issue, experimental setups have been developed using model organisms such as yeast. In this article, we review some of the key experiments that provide clues as to the extent to which these paradoxical and elusive features of chromosomally indispensable elements may become valuable in the natural context.
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Affiliation(s)
- Riku Kuse
- Laboratory of Chromosome Function and Regulation, Graduate School of Engineering, Kochi University of Technology, Kochi 782-8502, Japan
| | - Kojiro Ishii
- Laboratory of Chromosome Function and Regulation, Graduate School of Engineering, Kochi University of Technology, Kochi 782-8502, Japan
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Su J, Xu R, Mongia P, Toyofuku N, Nakagawa T. Fission yeast Rad8/HLTF facilitates Rad52-dependent chromosomal rearrangements through PCNA lysine 107 ubiquitination. PLoS Genet 2021; 17:e1009671. [PMID: 34292936 PMCID: PMC8297803 DOI: 10.1371/journal.pgen.1009671] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 06/18/2021] [Indexed: 11/19/2022] Open
Abstract
Gross chromosomal rearrangements (GCRs), including translocation, deletion, and inversion, can cause cell death and genetic diseases such as cancer in multicellular organisms. Rad51, a DNA strand exchange protein, suppresses GCRs by repairing spontaneous DNA damage through a conservative way of homologous recombination, gene conversion. On the other hand, Rad52 that catalyzes single-strand annealing (SSA) causes GCRs using homologous sequences. However, the detailed mechanism of Rad52-dependent GCRs remains unclear. Here, we provide genetic evidence that fission yeast Rad8/HLTF facilitates Rad52-dependent GCRs through the ubiquitination of lysine 107 (K107) of PCNA, a DNA sliding clamp. In rad51Δ cells, loss of Rad8 eliminated 75% of the isochromosomes resulting from centromere inverted repeat recombination, showing that Rad8 is essential for the formation of the majority of isochromosomes in rad51Δ cells. Rad8 HIRAN and RING finger mutations reduced GCRs, suggesting that Rad8 facilitates GCRs through 3’ DNA-end binding and ubiquitin ligase activity. Mms2 and Ubc4 but not Ubc13 ubiquitin-conjugating enzymes were required for GCRs. Consistent with this, mutating PCNA K107 rather than the well-studied PCNA K164 reduced GCRs. Rad8-dependent PCNA K107 ubiquitination facilitates Rad52-dependent GCRs, as PCNA K107R, rad8, and rad52 mutations epistatically reduced GCRs. In contrast to GCRs, PCNA K107R did not significantly change gene conversion rates, suggesting a specific role of PCNA K107 ubiquitination in GCRs. PCNA K107R enhanced temperature-sensitive growth defects of DNA ligase I cdc17-K42 mutant, implying that PCNA K107 ubiquitination occurs when Okazaki fragment maturation fails. Remarkably, K107 is located at the interface between PCNA subunits, and an interface mutation D150E bypassed the requirement of PCNA K107 and Rad8 ubiquitin ligase for GCRs. These data suggest that Rad8-dependent PCNA K107 ubiquitination facilitates Rad52-dependent GCRs by changing the PCNA clamp structure. Gross chromosomal rearrangements (GCRs), including translocation, can alter gene dosage and activity, resulting in genetic diseases such as cancer. However, GCRs can occur by some enzymes, including Rad52 recombinase, and result in chromosomal evolution. Therefore, GCRs are not only pathological but also physiological phenomena from an evolutionary point of view. However, the detailed mechanism of GCRs remains unclear. Here, using fission yeast, we show that the homolog of human HLTF, Rad8 causes GCRs through noncanonical ubiquitination of proliferating cellular nuclear antigen (PCNA) at a lysine 107 (K107). Rad51, a DNA strand exchange protein, suppresses the formation of isochromosomes whose arms mirror each another and chromosomal truncation. We found that, like Rad52, Rad8 is required for isochromosome formation but not chromosomal truncation in rad51Δ cells, showing a specific role of Rad8 in homology-mediated GCRs. Mutations in Rad8 ubiquitin E3 ligase RING finger domain, Mms2-Ubc4 ubiquitin-conjugating enzymes, and PCNA K107 reduced GCRs in rad51Δ cells, suggesting that Rad8-Mms2-Ubc4-dependent PCNA K107 ubiquitination facilitates GCRs. PCNA trimers form a DNA sliding clamp. The K107 residue is located at the PCNA-PCNA interface, and an interface mutation D150E restored GCRs in PCNA K107R mutant cells. This study provides genetic evidence that Rad8-dependent PCNA K107 ubiquitination facilitates GCRs by changing the PCNA clamp structure.
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Affiliation(s)
- Jie Su
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Ran Xu
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Piyusha Mongia
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Naoko Toyofuku
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Takuro Nakagawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
- * E-mail:
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Li B. Keeping Balance Between Genetic Stability and Plasticity at the Telomere and Subtelomere of Trypanosoma brucei. Front Cell Dev Biol 2021; 9:699639. [PMID: 34291053 PMCID: PMC8287324 DOI: 10.3389/fcell.2021.699639] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/08/2021] [Indexed: 12/13/2022] Open
Abstract
Telomeres, the nucleoprotein complexes at chromosome ends, are well-known for their essential roles in genome integrity and chromosome stability. Yet, telomeres and subtelomeres are frequently less stable than chromosome internal regions. Many subtelomeric genes are important for responding to environmental cues, and subtelomeric instability can facilitate organismal adaptation to extracellular changes, which is a common theme in a number of microbial pathogens. In this review, I will focus on the delicate and important balance between stability and plasticity at telomeres and subtelomeres of a kinetoplastid parasite, Trypanosoma brucei, which causes human African trypanosomiasis and undergoes antigenic variation to evade the host immune response. I will summarize the current understanding about T. brucei telomere protein complex, the telomeric transcript, and telomeric R-loops, focusing on their roles in maintaining telomere and subtelomere stability and integrity. The similarities and differences in functions and underlying mechanisms of T. brucei telomere factors will be compared with those in human and yeast cells.
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Affiliation(s)
- Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, Cleveland, OH, United States.,Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, United States.,Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States.,Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH, United States
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Roisné-Hamelin F, Pobiega S, Jézéquel K, Miron S, Dépagne J, Veaute X, Busso D, Du MHL, Callebaut I, Charbonnier JB, Cuniasse P, Zinn-Justin S, Marcand S. Mechanism of MRX inhibition by Rif2 at telomeres. Nat Commun 2021; 12:2763. [PMID: 33980827 PMCID: PMC8115599 DOI: 10.1038/s41467-021-23035-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 04/13/2021] [Indexed: 02/06/2023] Open
Abstract
Specific proteins present at telomeres ensure chromosome end stability, in large part through unknown mechanisms. In this work, we address how the Saccharomyces cerevisiae ORC-related Rif2 protein protects telomere. We show that the small N-terminal Rif2 BAT motif (Blocks Addition of Telomeres) previously known to limit telomere elongation and Tel1 activity is also sufficient to block NHEJ and 5' end resection. The BAT motif inhibits the ability of the Mre11-Rad50-Xrs2 complex (MRX) to capture DNA ends. It acts through a direct contact with Rad50 ATP-binding Head domains. Through genetic approaches guided by structural predictions, we identify residues at the surface of Rad50 that are essential for the interaction with Rif2 and its inhibition. Finally, a docking model predicts how BAT binding could specifically destabilise the DNA-bound state of the MRX complex. From these results, we propose that when an MRX complex approaches a telomere, the Rif2 BAT motif binds MRX Head in its ATP-bound resting state. This antagonises MRX transition to its DNA-bound state, and favours a rapid return to the ATP-bound state. Unable to stably capture the telomere end, the MRX complex cannot proceed with the subsequent steps of NHEJ, Tel1-activation and 5' resection.
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Affiliation(s)
- Florian Roisné-Hamelin
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Sabrina Pobiega
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Kévin Jézéquel
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Simona Miron
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Jordane Dépagne
- CIGEx, Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Xavier Veaute
- CIGEx, Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Didier Busso
- CIGEx, Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France
| | - Marie-Hélène Le Du
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Isabelle Callebaut
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie de Physique des Matériaux et de Cosmochimie (IMPMC), Paris, France
| | - Jean-Baptiste Charbonnier
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Philippe Cuniasse
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Sophie Zinn-Justin
- Université Paris-Saclay, CNRS, CEA, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Stéphane Marcand
- Université de Paris, Université Paris-Saclay, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France.
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