scholarly journals Loss of Rereplication Control in Saccharomyces cerevisiae Results in Extensive DNA Damage

2005 ◽  
Vol 16 (1) ◽  
pp. 421-432 ◽  
Author(s):  
Brian M. Green ◽  
Joachim J. Li
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Damage ◽  
Genome Stability ◽  
Eukaryotic Cell ◽  
Entire Genome ◽  
Yeast Saccharomyces Cerevisiae ◽  
Checkpoint Response ◽  
Checkpoint Protein ◽  
C Terminus

To maintain genome stability, the entire genome of a eukaryotic cell must be replicated once and only once per cell cycle. In many organisms, multiple overlapping mechanisms block rereplication, but the consequences of deregulating these mechanisms are poorly understood. Here, we show that disrupting these controls in the budding yeast Saccharomyces cerevisiae rapidly blocks cell proliferation. Rereplicating cells activate the classical DNA damage-induced checkpoint response, which depends on the BRCA1 C-terminus checkpoint protein Rad9. In contrast, Mrc1, a checkpoint protein required for recognition of replication stress, does not play a role in the response to rereplication. Strikingly, rereplicating cells accumulate subchromosomal DNA breakage products. These rapid and severe consequences suggest that even limited and sporadic rereplication could threaten the genome with significant damage. Hence, even subtle disruptions in the cell cycle regulation of DNA replication may predispose cells to the genomic instability associated with tumorigenesis.

scholarly journals MEC3, MEC1, and DDC2Are Essential Components of a Telomere Checkpoint Pathway Required for Cell Cycle Arrest during Senescence in Saccharomyces cerevisiae

2002 ◽  
Vol 13 (8) ◽  
pp. 2626-2638 ◽  
Author(s):  
Shinichiro Enomoto ◽  
Lynn Glowczewski ◽  
Judith Berman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Damage ◽  
Telomerase Activity ◽  
Cellular Level ◽  
Dna Damage Checkpoint ◽  
Average Growth ◽  
Progressive Decline ◽  
Checkpoint Response ◽  
Essential Components

When telomerase is absent and/or telomeres become critically short, cells undergo a progressive decline in viability termed senescence. The telomere checkpoint model predicts that cells will respond to a damaged or critically short telomere by transiently arresting and activating repair of the telomere. We examined the senescence of telomerase-deficient Saccharomyces cerevisiae at the cellular level to ask if the loss of telomerase activity triggers a checkpoint response. As telomerase-deficient mutants were serially subcultured, cells exhibited a progressive decline in average growth rate and an increase in the number of cells delayed in the G2/M stage of the cell cycle. MEC3, MEC1, andDDC2, genes important for the DNA damage checkpoint response, were required for the cell cycle delay in telomerase-deficient cells. In contrast, TEL1,RAD9, and RAD53, genes also required for the DNA damage checkpoint response, were not required for the G2/M delay in telomerase-deficient cells. We propose that the telomere checkpoint is distinct from the DNA damage checkpoint and requires a specific set of gene products to delay the cell cycle and presumably to activate telomerase and/or other telomere repair activities.

scholarly journals Telomerase subunit Est2 marks internal sites that are prone to accumulate DNA damage

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Satyaprakash Pandey ◽  
Mona Hajikazemi ◽  
Theresa Zacheja ◽  
Stephanie Schalbetter ◽  
Jonathan Baxter ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Damage ◽  
Binding Sites ◽  
Genome Stability ◽  
Main Function ◽  
Adverse Conditions ◽  
G2 Phase ◽  
Telomerase Regulation ◽  
Novel Model

Abstract Background The main function of telomerase is at the telomeres but under adverse conditions telomerase can bind to internal regions causing deleterious effects as observed in cancer cells. Results By mapping the global occupancy of the catalytic subunit of telomerase (Est2) in the budding yeast Saccharomyces cerevisiae, we reveal that it binds to multiple guanine-rich genomic loci, which we termed “non-telomeric binding sites” (NTBS). We characterize Est2 binding to NTBS. Contrary to telomeres, Est2 binds to NTBS in G1 and G2 phase independently of Est1 and Est3. The absence of Est1 and Est3 renders telomerase inactive at NTBS. However, upon global DNA damage, Est1 and Est3 join Est2 at NTBS and telomere addition can be observed indicating that Est2 occupancy marks NTBS regions as particular risks for genome stability. Conclusions Our results provide a novel model of telomerase regulation in the cell cycle using internal regions as “parking spots” of Est2 but marking them as hotspots for telomere addition.

G1 cyclins regulate proliferation of the budding yeast Saccharomyces cerevisiae

1992 ◽  
Vol 70 (10-11) ◽  
pp. 946-953
Author(s):  
Adele Rowley ◽  
Gerald C. Johnston ◽  
Richard A. Singer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Protein Kinase ◽  
Budding Yeast ◽  
Cell Types ◽  
Eukaryotic Cell ◽  
Yeast Saccharomyces Cerevisiae ◽  
Functional Conservation ◽  
Cycle Regulation

The eukaryotic cell cycle is regulated at two points, the G1-S and G2-M boundaries. The molecular basis for these regulatory activities has recently been elucidated, in large part by the use of molecular and genetic analyses using unicellular yeast. The molecular characterization of cell-cycle regulation has revealed striking functional conservation among evolutionarily diverse cell types. For many eukaryotic cells, regulation of cell proliferation occurs primarily in the G1 interval. The G2 regulatory step, termed start, requires the activation of a highly conserved p34 protein kinase by association with a functionally redundant family of proteins, the G1 cyclins. Here we review studies using the genetically tractable budding yeast Saccharomyces cerevisiae, which have provided insight into the role of G1 cyclins in the regulation of start.Key words: cell cycle, cyclin proteins, cdc2 protein kinase, start.

scholarly journals The Chromatin-binding Protein Spn1 contributes to Genome Instability in Saccharomyces cerevisiae

2018 ◽  
Author(s):  
Alison K. Thurston ◽  
Catherine A. Radebaugh ◽  
Adam R. Almeida ◽  
Juan Lucas Argueso ◽  
Laurie A. Stargell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Damage ◽  
Genome Stability ◽  
Damage Tolerance ◽  
Genome Instability ◽  
Chromatin Binding ◽  
Dna Damage Tolerance ◽  
Template Switch

AbstractCells expend a large amount of energy to maintain their DNA sequence. DNA repair pathways, cell cycle checkpoint activation, proofreading polymerases, and chromatin structure are ways in which the cell minimizes changes to the genome. During replication, the DNA damage tolerance pathway allows the replication forks to bypass damage on the template strand. This avoids prolonged replication fork stalling, which can contribute to genome instability. The DNA damage tolerance pathway includes two sub-pathways: translesion synthesis and template switch. Post-translational modification of PCNA and the histone tails, cell cycle phase, and local DNA structure have all been shown to influence sub-pathway choice. Chromatin architecture contributes to maintaining genome stability by providing physical protection of the DNA and by regulating DNA processing pathways. As such, chromatin-binding factors have been implicated in maintaining genome stability. Using Saccharomyces cerevisiae, we examined the role of Spn1, a chromatin binding and transcription elongation factor, in DNA damage tolerance. Expression of a mutant allele of SPN1 results in increased resistance to the DNA damaging agent methyl methanesulfonate, lower spontaneous and damage-induced mutation rates, along with increased chronological lifespan. We attribute these effects to an increased usage of the template switch branch of the DNA damage tolerance pathway in the spn1 strain. This provides evidence for a role of wild type Spn1 in promoting genome instability, as well as having ties to overcoming replication stress and contributing to chronological aging.

scholarly journals Adaptive regrowth in respiratory deficient strain of yeast Saccharomyces cerevisiae due to deletion of YKU70 gene

2020 ◽  
Vol 82 (3) ◽  
pp. 53-58
Author(s):  
Yu. Rymar ◽  
S. Rushkovsky ◽  
S. Demidov ◽  
L. Velykozhon ◽  
O. Pronina ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Genome Stability ◽  
Malignant Tumors ◽  
Nuclear Genome ◽  
Pcr Analysis ◽  
Restrictive Temperature ◽  
Yeast Saccharomyces Cerevisiae ◽  
Petite Mutant ◽  
Respiratory Deficient

It is known that significant causes of malignant tumors are destabilization of the nuclear genome and mitochondrial dysfunction. Adaptive regrowth in yeast colonies (the appearance of cell subpopulations more adapted to unfavorable conditions under conditions of the death of the original culture) is used as a model of the initial stages of carcinogenesis. To study the features of the formation of adaptive regrowth, a reparationdefective and respiratory-deficient yeast strain of Saccharomyces cerevisiae was created. The thermosensitive mutation in the yku70 gene was used as an inducer of nuclear genome instability (at 37 оC it causes cell cycle arrest due to a reduction of the length of telomeric regions of chromosomes). Damage to the mitochondrial DNA of the ∆yku70 strain led to its respiratory deficiency (petite mutation). The isolated petite mutant ∆yku70 strain was cultured at optimal 28 оC and restrictive 37 оC temperatures, the state of the cell suspension was evaluated by light and fluorescence microscopy, to determine the viability of cells was used the analysis of microcolonies growth. Isolation of adaptive regrowth clones and analysis of their properties by the method of serial dilutions were conducted. To assess the genome stability of selected clones of adaptive regrowth, PCR analysis of the microsatellite sequences YOR267C, SC8132X, SCPTSY7 was conducted. When culturing the petite mutant of the strain ∆yku70 at a restrictive temperature of 37 оC for 7 days, the formation of viable subpopulations was detected, which can overcome the arrest of the cell cycle in the G2 / M phase. Further analysis of the isolated clones of adaptive regrowth showed that they differ in cell survival at restrictive temperature, resistance to UV radiation and the ability to form adaptive regrowth on colonies. In the analysis of microsatellite repeats in adaptive regrowth clones, no manifestations of instability of the studied sequences were detected.

Conserved structural motifs in cyclins identified by sequence analysis

1991 ◽  
Vol 99 (3) ◽  
pp. 669-674 ◽  
Author(s):  
J.H. Nugent ◽  
C.E. Alfa ◽  
T. Young ◽  
J.S. Hyams
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Amino Acids ◽  
Phosphorylation Site ◽  
Degradation Pathway ◽  
Eukaryotic Cell ◽  
Database Search ◽  
Yeast Saccharomyces Cerevisiae ◽  
Regulatory Subunits ◽  
Controlling Elements

Cyclins, as regulatory subunits of the ubiquitous p34cdc2 protein kinase, act as key controlling elements of the eukaryotic cell cycle. We have examined published sequences of A- and B-type cyclins for both amino acid and secondary structure homologies. In particular, we sought regions of homology outside the recognised area of sequence conservation known as the “cyclin box”, as well as conserved features predicted to lie at the protein surface. Our analysis demonstrates the existence of a number of islands of homology outside the cyclin box, and indicates candidate residues for phosphorylation. One of these, a motif containing the amino acids SPXXXE/D is also present in fission yeast p13suc1, another protein known to interact with p34cdc2. This motif may define a possible p34cdc2 binding or phosphorylation site. A database search revealed that the CDC25 and SCD25 genes of the budding yeast Saccharomyces cerevisiae also contain some of the newly identified motifs, perhaps indicating a common regulatory or degradation pathway.

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