scholarly journals Recombination-Based Telomere Maintenance Is Dependent on Tel1-MRN and Rap1 and Inhibited by Telomerase, Taz1, and Ku in Fission Yeast

2007 ◽  
Vol 28 (5) ◽  
pp. 1443-1455 ◽  
Author(s):  
Lakxmi Subramanian ◽  
Bettina A. Moser ◽  
Toru M. Nakamura
Keyword(s):  
Dna Repair ◽  
Fission Yeast ◽  
Catalytic Subunit ◽  
Telomere Maintenance ◽  
Yeast Cells ◽  
Eukaryotic Cells ◽  
Checkpoint Kinase ◽  
Telomere Binding Protein ◽  
Evolutionarily Conserved ◽  
Linear Chromosomes

ABSTRACT Fission yeast cells survive loss of the telomerase catalytic subunit Trt1 (TERT) through recombination-based telomere maintenance or through chromosome circularization. Although trt1Δ survivors with linear chromosomes can be obtained, they often spontaneously circularize their chromosomes. Therefore, it was difficult to establish genetic requirements for telomerase-independent telomere maintenance. In contrast, when the telomere-binding protein Taz1 is also deleted, taz1Δ trt1Δ cells are able to stably maintain telomeres. Thus, taz1Δ trt1Δ cells can serve as a valuable tool in understanding the regulation of telomerase-independent telomere maintenance. In this study, we show that the checkpoint kinase Tel1 (ATM) and the DNA repair complex Rad32-Rad50-Nbs1 (MRN) are required for telomere maintenance in taz1Δ trt1Δ cells. Surprisingly, Rap1 is also essential for telomere maintenance in taz1Δ trt1Δ cells, even though recruitment of Rap1 to telomeres depends on Taz1. Expression of catalytically inactive Trt1 can efficiently inhibit recombination-based telomere maintenance, but the inhibition requires both Est1 and Ku70. While Est1 is essential for recruitment of Trt1 to telomeres, Ku70 is dispensable. Thus, we conclude that Taz1, TERT-Est1, and Ku70-Ku80 prevent telomere recombination, whereas MRN-Tel1 and Rap1 promote recombination-based telomere maintenance. Evolutionarily conserved proteins in higher eukaryotic cells might similarly contribute to telomere recombination.

scholarly journals Telomere Binding of Checkpoint Sensor and DNA Repair Proteins Contributes to Maintenance of Functional Fission Yeast Telomeres

Genetics ◽  
2002 ◽  
Vol 161 (4) ◽  
pp. 1437-1452 ◽  
Author(s):  
Toru M Nakamura ◽  
Bettina A Moser ◽  
Paul Russell
Keyword(s):  
Dna Repair ◽  
Fission Yeast ◽  
Telomere Maintenance ◽  
Cycle Arrest ◽  
Telomere Protection ◽  
Telomere Binding Protein ◽  
Dna Repair Proteins ◽  
A Cell ◽  
Linear Chromosomes ◽  
Related Proteins

Abstract Telomeres, the ends of linear chromosomes, are DNA double-strand ends that do not trigger a cell cycle arrest and yet require checkpoint and DNA repair proteins for maintenance. Genetic and biochemical studies in the fission yeast Schizosaccharomyces pombe were undertaken to understand how checkpoint and DNA repair proteins contribute to telomere maintenance. On the basis of telomere lengths of mutant combinations of various checkpoint-related proteins (Rad1, Rad3, Rad9, Rad17, Rad26, Hus1, Crb2, Chk1, Cds1), Tel1, a telomere-binding protein (Taz1), and DNA repair proteins (Ku70, Rad32), we conclude that Rad3/Rad26 and Tel1/Rad32 represent two pathways required to maintain telomeres and prevent chromosome circularization. Rad1/Rad9/Hus1/Rad17 and Ku70 are two additional epistasis groups, which act in the Rad3/Rad26 pathway. However, Rad3/Rad26 must have additional target(s), as cells lacking Tel1/Rad32, Rad1/Rad9/Hus1/Rad17, and Ku70 groups did not circularize chromosomes. Cells lacking Rad3/Rad26 and Tel1/Rad32 senesced faster than a telomerase trt1Δ mutant, suggesting that these pathways may contribute to telomere protection. Deletion of taz1 did not suppress chromosome circularization in cells lacking Rad3/Rad26 and Tel1/Rad32, also suggesting that two pathways protect telomeres. Chromatin immunoprecipitation analyses found that Rad3, Rad1, Rad9, Hus1, Rad17, Rad32, and Ku70 associate with telomeres. Thus, checkpoint sensor and DNA repair proteins contribute to telomere maintenance and protection through their association with telomeres.

scholarly journals Fission Yeast Taz1 and RPA Are Synergistically Required to Prevent Rapid Telomere Loss

2007 ◽  
Vol 18 (6) ◽  
pp. 2378-2387 ◽  
Author(s):  
Tatsuya Kibe ◽  
Yuuki Ono ◽  
Koichiro Sato ◽  
Masaru Ueno
Keyword(s):  
Fission Yeast ◽  
Binding Protein ◽  
Protein A ◽  
Telomere Maintenance ◽  
Helicase Domain ◽  
Recq Helicase ◽  
Telomeric Dna ◽  
Telomere Binding Protein ◽  
Recombination Repair ◽  
Telomere Loss

The telomere complex must allow nucleases and helicases to process chromosome ends to make them substrates for telomerase, while preventing these same activities from disrupting chromosome end-protection. Replication protein A (RPA) binds to single-stranded DNA and is required for DNA replication, recombination, repair, and telomere maintenance. In fission yeast, the telomere binding protein Taz1 protects telomeres and negatively regulates telomerase. Here, we show that taz1-d rad11-D223Y double mutants lose their telomeric DNA, indicating that RPA (Rad11) and Taz1 are synergistically required to prevent telomere loss. Telomere loss in the taz1-d rad11-D223Y double mutants was suppressed by additional mutation of the helicase domain in a RecQ helicase (Rqh1), or by overexpression of Pot1, a single-strand telomere binding protein that is essential for protection of chromosome ends. From our results, we propose that in the absence of Taz1 and functional RPA, Pot1 cannot function properly and the helicase activity of Rqh1 promotes telomere loss. Our results suggest that controlling the activity of Rqh1 at telomeres is critical for the prevention of genomic instability.

scholarly journals Protection and replication of telomeres in fission yeastThis paper is one of a selection of papers published in this Special Issue, entitled 30th Annual International Asilomar Chromatin and Chromosomes Conference, and has undergone the Journal’s usual peer review process.

2009 ◽  
Vol 87 (5) ◽  
pp. 747-758 ◽  
Author(s):  
Bettina A. Moser ◽  
Toru M. Nakamura
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Review Process ◽  
Peer Review Process ◽  
Yeast Cells ◽  
Special Issue ◽  
Yeast Saccharomyces Cerevisiae ◽  
Linear Chromosomes ◽  
Selection Of ◽  
The Way

Telomeres, the natural ends of linear chromosomes, must be protected and completely replicated to guarantee genomic stability in eukaryotic cells. However, the protected state of telomeres is not compatible with recruitment of telomerase, an enzyme responsible for extending telomeric G-rich repeats during S-phase; thus, telomeres must undergo switches from a protected state to an accessible state during the cell cycle. In this minireview, we will summarize recent advances in our understanding of proteins involved in the protection and replication of telomeres, and the way these factors are dynamically recruited to telomeres during the cell cycle. We will focus mainly on recent results from fission yeast Schizosaccharomyces pombe , and compare them with results from budding yeast Saccharomyces cerevisiae and mammalian cell studies. In addition, a model for the way in which fission yeast cells replicate telomeres will be presented.

scholarly journals Ccq1-Tpz1TPP1 interaction facilitates telomerase and SHREC association with telomeres in fission yeast

2015 ◽  
Vol 26 (21) ◽  
pp. 3857-3866 ◽  
Author(s):  
Bettina A. Moser ◽  
Olga N. Raguimova ◽  
Toru M. Nakamura
Keyword(s):  
Dna Damage ◽  
Fission Yeast ◽  
Telomere Maintenance ◽  
Dna Damage Checkpoint ◽  
Checkpoint Activation ◽  
Telomere Shortening ◽  
Progressive Loss ◽  
Evolutionarily Conserved ◽  
Repressor Complex

Evolutionarily conserved shelterin complex is essential for telomere maintenance in the fission yeast Schizosaccharomyces pombe. Elimination of the fission yeast shelterin subunit Ccq1 causes progressive loss of telomeres due to the inability to recruit telomerase, activates the DNA damage checkpoint, and loses heterochromatin at telomere/subtelomere regions due to reduced recruitment of the heterochromatin regulator complex Snf2/histone deacetylase–containing repressor complex (SHREC). The shelterin subunit Tpz1TPP1 directly interacts with Ccq1 through conserved C-terminal residues in Tpz1TPP1, and tpz1 mutants that fail to interact with Ccq1 show telomere shortening, checkpoint activation, and loss of heterochromatin. While we have previously concluded that Ccq1-Tpz1TPP1 interaction contributes to Ccq1 accumulation and telomerase recruitment based on analysis of tpz1 mutants that fail to interact with Ccq1, another study reported that loss of Ccq1-Tpz1TPP1 interaction does not affect accumulation of Ccq1 or telomerase. Furthermore, it remained unclear whether loss of Ccq1-Tpz1TPP1 interaction affects SHREC accumulation at telomeres. To resolve these issues, we identified and characterized a series of ccq1 mutations that disrupt Ccq1-Tpz1TPP1 interaction. Characterization of these ccq1 mutants established that Ccq1-Tpz1TPP1 interaction contributes to optimal binding of the Ccq1-SHREC complex, and is critical for Rad3ATR/Tel1ATM-dependent Ccq1 Thr93 phosphorylation and telomerase recruitment.

scholarly journals p34cdc2 acts as a lamin kinase in fission yeast.

1991 ◽  
Vol 112 (5) ◽  
pp. 797-807 ◽  
Author(s):  
T Enoch ◽  
M Peter ◽  
P Nurse ◽  
E A Nigg
Keyword(s):  
Fission Yeast ◽  
Kinase Activity ◽  
Nuclear Lamina ◽  
Yeast Cells ◽  
Eukaryotic Cells ◽  
Temperature Sensitive ◽  
Nuclear Lamins ◽  
Cdc2 Gene ◽  
Genetic Techniques ◽  
Higher Eukaryotes

The nuclear lamina is an intermediate filament network that underlies the nuclear membrane in higher eukaryotic cells. During mitosis in higher eukaryotes, nuclear lamins are phosphorylated by a mitosis-specific kinase and this induces disassembly of the lamina structure. Recently, p34cdc2 protein kinase purified from starfish has been shown to induce phosphorylation of lamin proteins and disassembly of the nuclear lamina when incubated with isolated chick nuclei suggesting that p34cdc2 is likely to be the mitotic lamin kinase (Peter, M., J. Nakagawa, M. Dorée, J.C. Labbe, and E.A. Nigg. 1990b. Cell. 45:145-153). To confirm and extend these studies using genetic techniques, we have investigated the role of p34cdc2 in lamin phosphorylation in the fission yeast. As fission yeast lamins have not been identified, we have introduced a cDNA encoding the chicken lamin B2 protein into fission yeast. We report here that the chicken lamin B2 protein expressed in fission yeast is assembled into a structure that associates with the nucleus during interphase and becomes dispersed throughout the cytoplasm when cells enter mitosis. Mitotic reorganization correlates with phosphorylation of the chicken lamin B2 protein by a mitosis-specific yeast lamin kinase with similarities to the mitotic lamin kinase of higher eukaryotes. We show that a lamin kinase activity can be detected in cell-free yeast extracts and in p34cdc2 immunoprecipitates prepared from yeast cells arrested in mitosis. The fission yeast lamin kinase activity is temperature sensitive in extracts and immunoprecipitates prepared from strains bearing temperature-sensitive mutations in the cdc2 gene. These results in conjunction with the previously reported biochemical studies strongly suggest that disassembly of the nuclear lamina at mitosis in higher eukaryotic cells is a consequence of direct phosphorylation of nuclear lamins by p34cdc2.

The Fission Yeast spSet1p is a Histone H3-K4 Methyltransferase that Functions in Telomere Maintenance and DNA Repair in an ATM Kinase Rad3-dependent Pathway

2003 ◽  
Vol 326 (4) ◽  
pp. 1081-1094 ◽  
Author(s):  
Junko Kanoh ◽  
Stefania Francesconi ◽  
Ada Collura ◽  
Vera Schramke ◽  
Fuyuki Ishikawa ◽  
...  
Keyword(s):  
Dna Repair ◽  
Fission Yeast ◽  
Histone H3 ◽  
Telomere Maintenance ◽  
Atm Kinase ◽  
Dependent Pathway

scholarly journals RNA-DNA hybrids support recombination-based telomere maintenance in fission yeast

2018 ◽  
Author(s):  
Yan Hu ◽  
Henrietta W. Bennett ◽  
Na Liu ◽  
Martin Moravec ◽  
Jessica F. Williams ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Telomeric Repeat ◽  
Telomere Maintenance ◽  
Telomeric Dna ◽  
Homology Directed Repair ◽  
Alternative Lengthening ◽  
Linear Chromosomes ◽  
Severe Growth ◽  
Telomere Erosion

ABSTRACTA 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 orthologue, 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 up-regulation of telomere-engaged TERRA or altered recruitment of shelterin components can support telomerase-independent telomere maintenance.

scholarly journals Role of Fission Yeast Primase Catalytic Subunit in the Replication Checkpoint

2001 ◽  
Vol 12 (1) ◽  
pp. 115-128 ◽  
Author(s):  
Dominic J. F. Griffiths ◽  
Vivian F. Liu ◽  
Paul Nurse ◽  
Teresa S.-F. Wang
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Fission Yeast ◽  
Cellular Localization ◽  
Catalytic Subunit ◽  
Checkpoint Kinase ◽  
Replication Checkpoint ◽  
Checkpoint Response ◽  
Allele Specific ◽  
Primase Complex

To investigate the cell cycle checkpoint response to aberrant S phase-initiation, we analyzed mutations of the two DNA primase subunit genes of Schizosaccharomyces pombe,spp1 + and spp2 +(S. pombe primase 1 and 2).spp1 + encodes the catalytic subunit that synthesizes the RNA primer, which is then utilized by Polα to synthesize the initiation DNA. Here, we reported the isolation of the fission yeast spp1 + gene and cDNA and the characterization of Spp1 protein and its cellular localization during the cell cycle. Spp1 is essential for cell viability, and thermosensitive mutants of spp1 + exhibit an allele-specific abnormal mitotic phenotype. Mutations ofspp1 + reduce the steady-state cellular levels of Spp1 protein and compromised the formation of Polα–primase complex. The spp1 mutant displaying an aberrant mitotic phenotype also fails to properly activate the Chk1 checkpoint kinase, but not the Cds1 checkpoint kinase. Mutational analysis of Polα has previously shown that activation of the replication checkpoint requires the initiation of DNA synthesis by Polα. Together, these have led us to propose that suboptimal cellular levels of polα–primase complex due to the allele-specific mutations of Spp1 might not allow Polα to synthesize initiation DNA efficiently, resulting in failure to activate a checkpoint response. Thus, a functional Spp1 is required for the Chk1-mediated, but not the Cds1-mediated, checkpoint response after an aberrant initiation of DNA synthesis.

Sign in / Sign up

Export Citation Format

Share Document