scholarly journals The Human F-Box DNA Helicase FBH1 Faces Saccharomyces cerevisiae Srs2 and Postreplication Repair Pathway Roles

2007 ◽  
Vol 27 (21) ◽  
pp. 7439-7450 ◽  
Author(s):  
Irene Chiolo ◽  
Marco Saponaro ◽  
Anastasia Baryshnikova ◽  
Jeong-Hoon Kim ◽  
Yeon-Soo Seo ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Self Regulation ◽  
Dna Helicase ◽  
Genome Integrity ◽  
Helicase Domain ◽  
Postreplication Repair ◽  
Scf Ubiquitin Ligase ◽  
Human Orthologue ◽  
Eukaryotic Organisms

ABSTRACTTheSaccharomyces cerevisiaeSrs2 UvrD DNA helicase controls genome integrity by preventing unscheduled recombination events. While Srs2 orthologues have been identified in prokaryotic and lower eukaryotic organisms, human orthologues of Srs2 have not been described so far. We found that the human F-box DNA helicase hFBH1 suppresses specific recombination defects ofS. cerevisiae srs2mutants, consistent with the finding that the helicase domain of hFBH1 is highly conserved with that of Srs2. Surprisingly, hFBH1 in the absence ofSRS2also suppresses the DNA damage sensitivity caused by inactivation of postreplication repair-dependent functions leading to PCNA ubiquitylation. The F-box domain of hFBH1, which is not present in Srs2, is crucial for hFBH1 functions in substituting for Srs2 and postreplication repair factors. Furthermore, our findings indicate that an intact F-box domain, acting as an SCF ubiquitin ligase, is required for the DNA damage-induced degradation of hFBH1 itself. Overall, our findings suggest that the hFBH1 helicase is a functional human orthologue of budding yeast Srs2 that also possesses self-regulation properties necessary to execute its recombination functions.

scholarly journals Saccharomyces cerevisiae Rrm3p DNA Helicase Promotes Genome Integrity by Preventing Replication Fork Stalling: Viability of rrm3 Cells Requires the Intra-S-Phase Checkpoint and Fork Restart Activities

2004 ◽  
Vol 24 (8) ◽  
pp. 3198-3212 ◽  
Author(s):  
Jorge Z. Torres ◽  
Sandra L. Schnakenberg ◽  
Virginia A. Zakian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Replication Fork ◽  
Opportunity To Learn ◽  
Normal Growth ◽  
Dna Helicase ◽  
S Phase ◽  
Exogenous Dna ◽  
Fork Stalling ◽  
S Phase Checkpoint

ABSTRACT Rrm3p is a 5′-to-3′ DNA helicase that helps replication forks traverse protein-DNA complexes. Its absence leads to increased fork stalling and breakage at over 1,000 specific sites located throughout the Saccharomyces cerevisiae genome. To understand the mechanisms that respond to and repair rrm3-dependent lesions, we carried out a candidate gene deletion analysis to identify genes whose mutation conferred slow growth or lethality on rrm3 cells. Based on synthetic phenotypes, the intra-S-phase checkpoint, the SRS2 inhibitor of recombination, the SGS1/TOP3 replication fork restart pathway, and the MRE11/RAD50/XRS2 (MRX) complex were critical for viability of rrm3 cells. DNA damage checkpoint and homologous recombination genes were important for normal growth of rrm3 cells. However, the MUS81/MMS4 replication fork restart pathway did not affect growth of rrm3 cells. These data suggest a model in which the stalled and broken forks generated in rrm3 cells activate a checkpoint response that provides time for fork repair and restart. Stalled forks are converted by a Rad51p-mediated process to intermediates that are resolved by Sgs1p/Top3p. The rrm3 system provides a unique opportunity to learn the fate of forks whose progress is impaired by natural impediments rather than by exogenous DNA damage.

scholarly journals Numerical and Spatial Patterning of Yeast Meiotic DNA Breaks by Tel1

2016 ◽  
Author(s):  
Neeman Mohibullah ◽  
Scott Keeney
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Deep Sequencing ◽  
Meiotic Recombination ◽  
Double Strand Breaks ◽  
Genome Integrity ◽  
Spatial Patterning ◽  
Dna Breaks ◽  
Strand Breaks ◽  
Context Dependent

AbstractThe Spo11-generated double-strand breaks (DSBs) that initiate meiotic recombination are dangerous lesions that can disrupt genome integrity, so meiotic cells regulate their number, timing, and distribution. Here, we use Spo11-oligonucleotide complexes, a byproduct of DSB formation, to examine the contribution of the DNA damage-responsive kinase Tel1 (ortholog of mammalian ATM) to this regulation in Saccharomyces cerevisiae. A tel1Δ mutant had globally increased amounts of Spo11-oligonucleotide complexes and altered Spo11-oligonucleotide lengths, consistent with conserved roles for Tel1 in control of DSB number and processing. A kinase-dead tell mutation also increased Spo11-oligonucleotide levels, but mutating known Tel1 phosphotargets on Hop1 and Rec114 did not. Deep sequencing of Spo11 oligonucleotides from tel1Δ mutants demonstrated that Tel1 shapes the nonrandom DSB distribution in ways that are distinct but partially overlapping with previously described contributions of the recombination regulator Zip3. Finally, we uncover a context-dependent role for Tel1 in hotspot competition, in which an artificial DSB hotspot inhibits nearby hotspots. Evidence for Tel1-dependent competition involving strong natural hotspots is also provided.

scholarly journals The Main Role of Srs2 in DNA Repair Depends on Its Helicase Activity, Rather than on Its Interactions with PCNA or Rad51

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Alex Bronstein ◽  
Lihi Gershon ◽  
Gilad Grinberg ◽  
Elisa Alonso-Perez ◽  
Martin Kupiec
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Genome Stability ◽  
Dna Helicase ◽  
Main Role ◽  
Helicase Domain ◽  
Helicase Activity ◽  
C Terminus ◽  
Srs2 Helicase

ABSTRACTHomologous recombination (HR) is a mechanism that repairs a variety of DNA lesions. Under certain circumstances, however, HR can generate intermediates that can interfere with other cellular processes such as DNA transcription or replication. Cells have therefore developed pathways that abolish undesirable HR intermediates. TheSaccharomyces cerevisiaeyeast Srs2 helicase has a major role in one of these pathways. Srs2 also works during DNA replication and interacts with the clamp PCNA. The relative importance of Srs2’s helicase activity, Rad51 removal function, and PCNA interaction in genome stability remains unclear. We created a newSRS2allele [srs2(1-850)] that lacks the whole C terminus, containing the interaction site for Rad51 and PCNA and interactions with many other proteins. Thus, the new allele encodes an Srs2 protein bearing only the activity of the DNA helicase. We find that the interactions of Srs2 with Rad51 and PCNA are dispensable for the main role of Srs2 in the repair of DNA damage in vegetative cells and for proper completion of meiosis. On the other hand, it has been shown that in cells impaired for the DNA damage tolerance (DDT) pathways, Srs2 generates toxic intermediates that lead to DNA damage sensitivity; we show that this negative Srs2 activity requires the C terminus of Srs2. Dissection of the genetic interactions of thesrs2(1-850) allele suggest a role for Srs2’s helicase activity in sister chromatid cohesion. Our results also indicate that Srs2’s function becomes more central in diploid cells.IMPORTANCEHomologous recombination (HR) is a key mechanism that repairs damaged DNA. However, this process has to be tightly regulated; failure to regulate it can lead to genome instability. The Srs2 helicase is considered a regulator of HR; it was shown to be able to evict the recombinase Rad51 from DNA. Cells lacking Srs2 exhibit sensitivity to DNA-damaging agents, and in some cases, they display defects in DNA replication. The relative roles of the helicase and Rad51 removal activities of Srs2 in genome stability remain unclear. To address this question, we created a new Srs2 mutant which has only the DNA helicase domain. Our study shows that only the DNA helicase domain is needed to deal with DNA damage and assist in DNA replication during vegetative growth and in meiosis. Thus, our findings shift the view on the role of Srs2 in the maintenance of genome integrity.

scholarly journals Relocation of rDNA repeats for repair is dependent on SUMO-mediated nucleolar release by the Cdc48/p97 segregase

2021 ◽  
Author(s):  
Matías Capella ◽  
Imke K. Mandemaker ◽  
Lucía Martín Caballero ◽  
Boris Pfander ◽  
Andreas G. Ladurner ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Homologous Recombination ◽  
Ribosomal Rna ◽  
Nuclear Membrane ◽  
Molecular Mechanisms ◽  
Genome Integrity ◽  
Repetitive Nature ◽  
Active Transcription ◽  
Rna Genes

AbstractRibosomal RNA genes (rDNA) are highly unstable and susceptible to rearrangement due to active transcription and their repetitive nature. Compartmentalization of rDNA in the nucleolus suppresses uncontrolled recombination. However, broken repeats must be released to the nucleoplasm to allow repair by homologous recombination. The process of rDNA relocation is conserved from yeast to humans, but the underlying molecular mechanisms are currently unknown. Here we show that DNA damage induces phosphorylation of the CLIP component Nur1, releasing nuclear membrane-tethered rDNA repeats from the nucleolus in Saccharomyces cerevisiae. Cooperating with Nur1 phosphorylation, SUMOylation targets the rDNA tethering complex for disassembly mediated by the segregase Cdc48/p97, which recognizes SUMOylated CLIP-cohibin through its cofactor, Ufd1. Consistent with the conservation of this mechanism, UFD1L depletion impairs rDNA release in human cells. The dynamic and regulated assembly and disassembly of the CLIP-cohibin complex is therefore a key, conserved determinant of nucleolar rDNA release and genome integrity.

scholarly journals Wss1 Is a SUMO-Dependent Isopeptidase That Interacts Genetically with the Slx5-Slx8 SUMO-Targeted Ubiquitin Ligase

2010 ◽  
Vol 30 (15) ◽  
pp. 3737-3748 ◽  
Author(s):  
Janet R. Mullen ◽  
Chi-Fu Chen ◽  
Steven J. Brill
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fusion Protein ◽  
Ubiquitin Ligase ◽  
Copy Number ◽  
Dna Helicase ◽  
Genome Integrity ◽  
Growth Defect ◽  
Sumo Fusion ◽  
Isopeptidase Activity

ABSTRACT Protein sumoylation plays an important but poorly understood role in controlling genome integrity. In Saccharomyces cerevisiae, the Slx5-Slx8 SUMO-targeted Ub ligase appears to be needed to ubiquitinate sumoylated proteins that arise in the absence of the Sgs1 DNA helicase. WSS1, a high-copy-number suppressor of a mutant SUMO, was implicated in this pathway because it shares phenotypes with SLX5-SLX8 mutants, including a wss1Δ sgs1Δ synthetic-fitness defect. Here we show that Wss1, a putative metalloprotease, physically binds SUMO and displays in vitro isopeptidase activity on poly-SUMO chains. Like that of SLX5, overexpression of WSS1 suppresses sgs1Δ slx5Δ lethality and the ulp1ts growth defect. Interestingly, although Wss1 is relatively inactive on ubiquitinated substrates and poly-Ub chains, it efficiently deubiquitinates a Ub-SUMO isopeptide conjugate and a Ub-SUMO fusion protein. Wss1 was further implicated in Ub metabolism on the basis of its physical association with proteasomal subunits. The results suggest that Wss1 is a SUMO-dependent isopeptidase that acts on sumoylated substrates as they undergo proteasomal degradation.

scholarly journals Nucleolar release of rDNA repeats for repair involves SUMO-mediated untethering by the Cdc48/p97 segregase

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Matías Capella ◽  
Imke K. Mandemaker ◽  
Lucía Martín Caballero ◽  
Fabian den Brave ◽  
Boris Pfander ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Homologous Recombination ◽  
Ribosomal Rna ◽  
Molecular Mechanisms ◽  
Human Cells ◽  
Ribosomal Rna Genes ◽  
Genome Integrity ◽  
Repetitive Nature ◽  
Rna Genes

AbstractRibosomal RNA genes (rDNA) are highly unstable and susceptible to rearrangement due to their repetitive nature and active transcriptional status. Sequestration of rDNA in the nucleolus suppresses uncontrolled recombination. However, broken repeats must be first released to the nucleoplasm to allow repair by homologous recombination. Nucleolar release of broken rDNA repeats is conserved from yeast to humans, but the underlying molecular mechanisms are currently unknown. Here we show that DNA damage induces phosphorylation of the CLIP-cohibin complex, releasing membrane-tethered rDNA from the nucleolus in Saccharomyces cerevisiae. Downstream of phosphorylation, SUMOylation of CLIP-cohibin is recognized by Ufd1 via its SUMO-interacting motif, which targets the complex for disassembly through the Cdc48/p97 chaperone. Consistent with a conserved mechanism, UFD1L depletion in human cells impairs rDNA release. The dynamic and regulated assembly and disassembly of the rDNA-tethering complex is therefore a key determinant of nucleolar rDNA release and genome integrity.

scholarly journals Requirement of Nse1, a Subunit of the Smc5-Smc6 Complex, for Rad52-Dependent Postreplication Repair of UV-Damaged DNA in Saccharomyces cerevisiae

2007 ◽  
Vol 27 (23) ◽  
pp. 8409-8418 ◽  
Author(s):  
Sergio R. Santa Maria ◽  
Venkateswarlu Gangavarapu ◽  
Robert E. Johnson ◽  
Louise Prakash ◽  
Satya Prakash
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Helicase ◽  
Template Switching ◽  
Postreplication Repair ◽  
Sumo Ligase ◽  
Fork Regression ◽  
A Subunit ◽  
Leading Strand ◽  
Dependent Pathway ◽  
Damaged Dna

ABSTRACT In Saccharomyces cerevisiae, postreplication repair (PRR) of UV-damaged DNA occurs by a Rad6-Rad18- and an Mms2-Ubc13-Rad5-dependent pathway or by a Rad52-dependent pathway. The Rad5 DNA helicase activity is specialized for promoting replication fork regression and template switching; previously, we suggested a role for the Rad5-dependent PRR pathway when the lesion is located on the leading strand and a role for the Rad52 pathway when the lesion is located on the lagging strand. In this study, we present evidence for the requirement of Nse1, a subunit of the Smc5-Smc6 complex, in Rad52-dependent PRR, and our genetic analyses suggest a role for the Nse1 and Mms21 E3 ligase activities associated with this complex in this repair mode. We discuss the possible ways by which the Smc5-Smc6 complex, including its associated ubiquitin ligase and SUMO ligase activities, might contribute to the Rad52-dependent nonrecombinational and recombinational modes of PRR.

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