Meiotic double-strand breaks in Schizosaccharomyces pombe

2000 ◽  
Vol 38 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Drora Zenvirth ◽  
Giora Simchen
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Double Strand Breaks ◽  
Strand Breaks

scholarly journals A conserved Ctp1/CtIP C-terminal peptide stimulates Mre11 endonuclease activity

2021 ◽  
Vol 118 (11) ◽  
pp. e2016287118
Author(s):  
Aleksandar Zdravković ◽  
James M. Daley ◽  
Arijit Dutta ◽  
Tatsuya Niwa ◽  
Yasuto Murayama ◽  
...  
Keyword(s):  
Amino Acids ◽  
Homologous Recombination ◽  
Schizosaccharomyces Pombe ◽  
Double Strand Breaks ◽  
Pivotal Role ◽  
Endonuclease Activity ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
C Terminus ◽  
Dna Strands

The Mre11-Rad50-Nbs1 complex (MRN) is important for repairing DNA double-strand breaks (DSBs) by homologous recombination (HR). The endonuclease activity of MRN is critical for resecting 5′-ended DNA strands at DSB ends, producing 3′-ended single-strand DNA, a prerequisite for HR. This endonuclease activity is stimulated by Ctp1, the Schizosaccharomyces pombe homolog of human CtIP. Here, with purified proteins, we show that Ctp1 phosphorylation stimulates MRN endonuclease activity by inducing the association of Ctp1 with Nbs1. The highly conserved extreme C terminus of Ctp1 is indispensable for MRN activation. Importantly, a polypeptide composed of the conserved 15 amino acids at the C terminus of Ctp1 (CT15) is sufficient to stimulate Mre11 endonuclease activity. Furthermore, the CT15 equivalent from CtIP can stimulate human MRE11 endonuclease activity, arguing for the generality of this stimulatory mechanism. Thus, we propose that Nbs1-mediated recruitment of CT15 plays a pivotal role in the activation of the Mre11 endonuclease by Ctp1/CtIP.

scholarly journals Mus81-Eme1-Dependent and -Independent Crossovers Form in Mitotic Cells during Double-Strand Break Repair in Schizosaccharomyces pombe

2007 ◽  
Vol 27 (10) ◽  
pp. 3828-3838 ◽  
Author(s):  
Justin C. Hope ◽  
Lissette Delgado Cruzata ◽  
Amit Duvshani ◽  
Jun Mitsumoto ◽  
Mohamed Maftahi ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Synthetic Lethality ◽  
Strand Break ◽  
Holliday Junctions ◽  
Double Strand Breaks ◽  
Strand Breaks ◽  
Fourfold Increase ◽  
Dependent Pathway ◽  
Mitotic Cells

ABSTRACT During meiosis, double-strand breaks (DSBs) lead to crossovers, thought to arise from the resolution of double Holliday junctions (HJs) by an HJ resolvase. In Schizosaccharomyces pombe, meiotic crossovers are produced primarily through a mechanism requiring the Mus81-Eme1 endonuclease complex. Less is known about the processes that produces crossovers during the repair of DSBs in mitotic cells. We employed an inducible DSB system to determine the role of Rqh1-Top3 and Mus81-Eme1 in mitotic DSB repair and crossover formation in S. pombe. In agreement with the meiotic data, crossovers are suppressed in cells lacking Mus81-Eme1. And relative to the wild type, rqh1Δ cells show a fourfold increase in crossover frequency. This suppression of crossover formation by Rqh1 is dependent on its helicase activity. We found that the synthetic lethality of cells lacking both Rqh1 and Eme1 is suppressed by loss of swi5 +, which allowed us to show that the excess crossovers formed in an rqh1Δ background are independent of Mus81-Eme1. This result suggests that a second process for crossover formation exists in S. pombe and is consistent with our finding that deletion of swi5 + restored meiotic crossovers in eme1Δ cells. Evidence suggesting that Rqh1 also acts downstream of Swi5 in crossover formation was uncovered in these studies. Our results suggest that during Rhp51-dependent repair of DSBs, Rqh1-Top3 suppresses crossovers in the Rhp57-dependent pathway while Mus81-Eme1 and possibly Rqh1 promote crossovers in the Swi5-dependent pathway.

Double-Strand Break-Induced Mitotic Intrachromosomal Recombination in the Fission Yeast Schizosaccharomyces pombe

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 341-357 ◽  
Author(s):  
Fekret Osman ◽  
Elizabeth A Fortunato ◽  
Suresh Subramani
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Strand Break ◽  
Double Strand Breaks ◽  
Direct Repeats ◽  
Wild Type ◽  
Site Specific ◽  
Strand Breaks ◽  
Intrachromosomal Recombination ◽  
Intervening Sequences ◽  
Ho Gene

Abstract The Saccharomyces cerevisiae HO gene and MATa cutting site were used to introduce site-specific double-strand breaks (DSBs) within intrachromosomal recombination substrates in Schizosaccharomyces pombe. The recombination substrates consisted of nontandem direct repeats of ade6 heteroalleles. DSB induction stimulated the frequency of recombinants 2000-fold. The spectrum of DSB-induced recombinants depended on whether the DSB was introduced within one of the ade6 repeats or in intervening unique DNA. When the DSB was introduced within unique DNA, over 99.8% of the recombinants lacked the intervening DNA but retained one copy of ade6 that was wild type or either one of the heteroalleles. When the DSB was located in duplicated DNA, 77% of the recombinants were similar to the deletion types described above, but the single ade6 copy was either wild type or exclusively that of the uncut repeat. The remaining 23% of the induced recombinants were gene convertants with two copies of ade6 and the intervening sequences; the ade6 heteroallele in which the DSB was induced was the recipient of genetic information. Half-sectored colonies were isolated, analyzed and interpreted as evidence of heteroduplex DNA formation. The results are discussed in terms of current models for recombination.

scholarly journals Schizosaccharomyces pombe Assays to Study Mitotic Recombination Outcomes

Genes ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 79
Author(s):  
Hannah M. Hylton ◽  
Bailey E. Lucas ◽  
Ruben C. Petreaca
Keyword(s):  
Dna Damage ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Molecular Mechanisms ◽  
Mitotic Recombination ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Damage Repair

The fission yeast—Schizosaccharomyces pombe—has emerged as a powerful tractable system for studying DNA damage repair. Over the last few decades, several powerful in vivo genetic assays have been developed to study outcomes of mitotic recombination, the major repair mechanism of DNA double strand breaks and stalled or collapsed DNA replication forks. These assays have significantly increased our understanding of the molecular mechanisms underlying the DNA damage response pathways. Here, we review the assays that have been developed in fission yeast to study mitotic recombination.

scholarly journals Competition between the Rad50 Complex and the Ku Heterodimer Reveals a Role for Exo1 in Processing Double-Strand Breaks but Not Telomeres

2003 ◽  
Vol 23 (15) ◽  
pp. 5186-5197 ◽  
Author(s):  
Kazunori Tomita ◽  
Akira Matsuura ◽  
Thomas Caspari ◽  
Antony M. Carr ◽  
Yufuko Akamatsu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Schizosaccharomyces Pombe ◽  
Protein Complex ◽  
Double Mutant ◽  
Double Strand Breaks ◽  
Methyl Methanesulfonate ◽  
Strand Breaks ◽  
Dna Break ◽  
Dna Ends

ABSTRACT The Mre11-Rad50-Nbs1(Xrs2) complex and the Ku70-Ku80 heterodimer are thought to compete with each other for binding to DNA ends. To investigate the mechanism underlying this competition, we analyzed both DNA damage sensitivity and telomere overhangs in Schizosaccharomyces pombe rad50-d, rad50-d pku70-d, rad50-d exo1-d, and pku70-d rad50-d exo1-d cells. We found that rad50 exo1 double mutants are more methyl methanesulfonate (MMS) sensitive than the respective single mutants. The MMS sensitivity of rad50-d cells was suppressed by concomitant deletion of pku70+ . However, the MMS sensitivity of the rad50 exo1 double mutant was not suppressed by the deletion of pku70+ . The G-rich overhang at telomere ends in taz1-d cells disappeared upon deletion of rad50+ , but the overhang reappeared following concomitant deletion of pku70+ . Our data suggest that the Rad50 complex can process DSB ends and telomere ends in the presence of the Ku heterodimer. However, the Ku heterodimer inhibits processing of DSB ends and telomere ends by alternative nucleases in the absence of the Rad50-Rad32 protein complex. While we have identified Exo1 as the alternative nuclease targeting DNA break sites, the identity of the nuclease acting on the telomere ends remains elusive.

Repair pathway choice for double-strand breaks

2020 ◽  
Vol 64 (5) ◽  
pp. 765-777 ◽  
Author(s):  
Yixi Xu ◽  
Dongyi Xu
Keyword(s):  
Cell Cycle ◽  
Double Strand Breaks ◽  
Homologous Region ◽  
Gene Repair ◽  
Repair Pathway ◽  
Dna Double Strand Breaks ◽  
Environmental Radiation ◽  
Strand Breaks ◽  
Dna End Resection ◽  
End Resection

Abstract Deoxyribonucleic acid (DNA) is at a constant risk of damage from endogenous substances, environmental radiation, and chemical stressors. DNA double-strand breaks (DSBs) pose a significant threat to genomic integrity and cell survival. There are two major pathways for DSB repair: nonhomologous end-joining (NHEJ) and homologous recombination (HR). The extent of DNA end resection, which determines the length of the 3′ single-stranded DNA (ssDNA) overhang, is the primary factor that determines whether repair is carried out via NHEJ or HR. NHEJ, which does not require a 3′ ssDNA tail, occurs throughout the cell cycle. 53BP1 and the cofactors PTIP or RIF1-shieldin protect the broken DNA end, inhibit long-range end resection and thus promote NHEJ. In contrast, HR mainly occurs during the S/G2 phase and requires DNA end processing to create a 3′ tail that can invade a homologous region, ensuring faithful gene repair. BRCA1 and the cofactors CtIP, EXO1, BLM/DNA2, and the MRE11–RAD50–NBS1 (MRN) complex promote DNA end resection and thus HR. DNA resection is influenced by the cell cycle, the chromatin environment, and the complexity of the DNA end break. Herein, we summarize the key factors involved in repair pathway selection for DSBs and discuss recent related publications.

Bestimmung der DNA-Schädigung in vitro

2010 ◽  
Vol 49 (S 01) ◽  
pp. S64-S68
Author(s):  
E. Dikomey
Keyword(s):  
Dna Damage ◽  
Cell Lines ◽  
Chromosome Aberrations ◽  
Genetic Factors ◽  
Double Strand Breaks ◽  
Strand Breaks ◽  
Cell Inactivation ◽  
Repair Mechanisms ◽  
Break Repair

SummaryIonising irradiation acts primarily via induction of DNA damage, among which doublestrand breaks are the most important lesions. These lesions may lead to lethal chromosome aberrations, which are the main reason for cell inactivation. Double-strand breaks can be repaired by several different mechanisms. The regulation of these mechanisms appears be fairly different for normal and tumour cells. Among different cell lines capacity of doublestrand break repair varies by only few percents and is known to be determined mostly by genetic factors. Knowledge about doublestrand break repair mechanisms and their regulation is important for the optimal application of ionising irradiation in medicine.

Sign in / Sign up

Export Citation Format

Share Document