Saccharomyces cerevisiae
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ABSTRACT:
PROVIDER: PRJNA267766 | ENA |
REPOSITORIES: ENA
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Project description:Eukaryotic cells respond to DNA double-strand breaks (DSBs) by activating a checkpoint that depends on the protein kinases Tel1/ATM and Mec1/ATR. Mec1/ATR is activated by RPA-coated single-stranded DNA (ssDNA), which arises upon nucleolytic degradation (resection) of the DSB. Emerging evidences indicate that RNA processing factors play critical, yet poorly understood, roles in genomic stability. Here, we provide evidence that the Saccharomyces cerevisiae RNA decay factors Xrn1, Rrp6 and Trf4 regulate Mec1/ATR activation by promoting generation of RPA-coated ssDNA. The lack of Xrn1 inhibits ssDNA generation at the DSB by preventing the loading of the MRX complex. By contrast, DSB resection is not affected in the absence of Rrp6 or Trf4, but their lack impairs the recruitment of RPA, and therefore of Mec1, to the DSB. Rrp6 and Trf4 inactivation affects neither Rad51/Rad52 association nor DSB repair by HR, suggesting that full Mec1 activation requires higher amount of RPA-coated ssDNA than HR-mediated repair. Noteworthy, deep transcriptome analyses do not identify common misregulated gene expression that could explain the observed phenotypes. Our results provide a novel link between RNA processing and genome stability. Strand-specific transcriptome analysis of biological replicates of WT cells (JKM139 strain) at T0, or 60 and 240 minutes after HO induction, and of xrn1∆, rrp6∆ and trf4∆ cells at T0.
2014-11-20 | E-GEOD-63444 | biostudies-arrayexpress
Project description:Eukaryotic cells respond to DNA double-strand breaks (DSBs) by activating a checkpoint that depends on the protein kinases Tel1/ATM and Mec1/ATR. Mec1/ATR is activated by RPA-coated single-stranded DNA (ssDNA), which arises upon nucleolytic degradation (resection) of the DSB. Emerging evidences indicate that RNA processing factors play critical, yet poorly understood, roles in genomic stability. Here, we provide evidence that the Saccharomyces cerevisiae RNA decay factors Xrn1, Rrp6 and Trf4 regulate Mec1/ATR activation by promoting generation of RPA-coated ssDNA. The lack of Xrn1 inhibits ssDNA generation at the DSB by preventing the loading of the MRX complex. By contrast, DSB resection is not affected in the absence of Rrp6 or Trf4, but their lack impairs the recruitment of RPA, and therefore of Mec1, to the DSB. Rrp6 and Trf4 inactivation affects neither Rad51/Rad52 association nor DSB repair by HR, suggesting that full Mec1 activation requires higher amount of RPA-coated ssDNA than HR-mediated repair. Noteworthy, deep transcriptome analyses do not identify common misregulated gene expression that could explain the observed phenotypes. Our results provide a novel link between RNA processing and genome stability.
2014-11-20 | GSE63444 | GEO
Project description:The ATR kinase is a master regulator of cellular responses to DNA damage and replication stress that is activated by a complex mechanism involving its binding partner ATRIP, RPA-coated ssDNA, the 9-1-1 complex and TopBP1. Here, we discovered a new ATR activation mechanism in human cells, mediated by the uncharacterized protein ETAA1 (Ewing’s tumor-associated antigen 1). From a comprehensive proteomic survey of protein recruitment to DNA double-strand break-modified chromatin, we identified ETAA1 as a factor that accumulates at DNA damage sites via an RPA-binding motif, and which has an important role in promoting cell survival and preventing replication fork breakage after genotoxic insults. Mechanistically, we show that ETAA1 harbors a conserved domain that potently and directly stimulates ATR kinase activity independent of TopBP1 and 9-1-1, and which is essential for the function of ETAA1 in the DNA damage response. Consistently, ablation of ETAA1 shows profound synthetic lethality with TopBP1 knockdown, resulting from massive replication fork collapse and abrogation of ATR-dependent signaling. Finally, we show that ETAA1 levels in cancer cell lines inversely correlate with their dependency on TopBP1 for ATR activation, and that overexpression of ETAA1 partially restores ATR-dependent signaling after loss of TopBP1. Together, these findings establish a new mechanism of ATR activation in human cells that operates in parallel with, but independent of, the canonical TopBP1-mediated pathway.
2016-09-30 | PXD003529 | Pride
Project description:RPA has been shown to protect single-stranded DNA (ssDNA) intermediates from instability and breakage. RPA binds ssDNA with sub-nanomolar affinity, yet dynamic turnover is required for downstream ssDNA transactions. How ultrahigh-affinity binding and dynamic turnover are achieved simultaneously is not well understood. Here we reveal that RPA has a strong propensity to assemble into dynamic condensates. In solution, purified RPA phase separates into liquid droplets with fusion and surface wetting behavior. Phase separation is stimulated by sub-stoichiometric amounts of ssDNA, but not RNA or double-stranded DNA, and ssDNA gets selectively enriched in RPA condensates. We find the RPA2 subunit required for condensation and multi-site phosphorylation of the RPA2 N-terminal intrinsically disordered region to regulate RPA self-interaction. Functionally, quantitative proximity proteomics links RPA condensation to telomere clustering and integrity in cancer cells. Collectively, our results suggest that RPA-coated ssDNA is contained in dynamic RPA condensates whose properties are important for genome organization and stability.
2023-03-15 | PXD036935 | Pride
Project description:The Mec1/ATR kinase is crucial for genome maintenance, although the mechanisms by which it controls DNA repair pathways remain elusive. Here we uncovered a role for Mec1/ATR in controlling homologous recombination (HR) factors in response to hyper-resection of DNA ends. Cells lacking RAD9, a checkpoint activator and an inhibitor of resection, exhibit Mec1-dependent hyper-phosphorylation of proteins associated with single strand DNA transactions, including the ssDNA binding protein Rfa2, the translocase/ubiquitin ligase Uls1 and the HR-regulatory Sgs1-Top3-Rmi1 (STR) complex. Extensive Mec1-dependent phosphorylation of the STR complex, mostly on the Sgs1 helicase subunit, promotes an interaction between STR and the DNA repair scaffolding protein Dpb11. Fusion of Sgs1 to phosphopeptide-binding domains of Dpb11 strongly impairs HR-mediated repair, supporting a model whereby Mec1 promotes recruitment of STR to the 9-1-1 clamp via Dpb11 to regulate recombinogenic processes.
2021-03-10 | PXD017289 | Pride
Project description:The Mec1/ATR kinase is crucial for genome maintenance, although the mechanisms by which it controls DNA repair pathways remain elusive. Here we uncovered a role for Mec1/ATR in controlling homologous recombination (HR) factors in response to hyper-resection of DNA ends. Cells lacking RAD9, a checkpoint activator and an inhibitor of resection, exhibit Mec1-dependent hyper-phosphorylation of proteins associated with single strand DNA transactions, including the ssDNA binding protein Rfa2, the translocase/ubiquitin ligase Uls1 and the HR-regulatory Sgs1-Top3-Rmi1 (STR) complex. Extensive Mec1-dependent phosphorylation of the STR complex, mostly on the Sgs1 helicase subunit, promotes an interaction between STR and the DNA repair scaffolding protein Dpb11.
2021-03-10 | PXD017286 | Pride
Project description:The Mec1/ATR kinase is crucial for genome maintenance, although the mechanisms by which it controls DNA repair pathways remain elusive. Here we uncovered a role for Mec1/ATR in controlling homologous recombination (HR) factors in response to hyper-resection of DNA ends. Cells lacking RAD9, a checkpoint activator and an inhibitor of resection, exhibit Mec1-dependent hyper-phosphorylation of proteins associated with single strand DNA transactions, including the ssDNA binding protein Rfa2, the translocase/ubiquitin ligase Uls1 and the HR-regulatory Sgs1-Top3-Rmi1 (STR) complex. Extensive Mec1-dependent phosphorylation of the STR complex, mostly on the Sgs1 helicase subunit, promotes an interaction between STR and the DNA repair scaffolding protein Dpb11.
2021-03-10 | PXD023438 | Pride
Project description:Single-stranded DNA (ssDNA) binding protein Replication Protein A (RPA) is essential for protecting ssDNA at replication forks. However, how RPA is loaded to replication forks remains unexplored. Here, we show that Regulator of Ty1 transposition protein 105 (Rtt105) binds RPA and is required for the association of RPA with replication forks. Cells lacking Rtt105 exhibit dramatic genome instability and severe defects in DNA replication. Intriguingly, both the RPA nuclear import and its ability to bind DNA replication forks were greatly compromised in rtt105 mutant cells, however, targeting RPA to the nucleus cannot rescue the defect of RPA binding to replication forks. Importantly, Rtt105 promotes the binding of RPA to ssDNA but does not associate with the final RPA-ssDNA complex in vitro. Moreover, single-molecule studies revealed that Rtt105 affects the binding mode of RPA to ssDNA. These results support a model in which Rtt105 functions as an RPA chaperone that escorts RPA to nucleus and assemble RPA onto ssDNA at replication forks.
2018-07-27 | GSE101536 | GEO
Project description:The Mec1/ATR kinase coordinates multiple cellular responses to replication stress. In addition to its canonical role in activating the checkpoint kinase Rad53, Mec1 also plays checkpoint-independent roles in genome maintenance that are not well understood. Here we employed a combined genetic-phosphoproteomic approach to manipulate Mec1 activation and globally monitor Mec1 signaling, allowing us to delineate distinct checkpoint-independent modes of Mec1 action. Using cells in which endogenous Mec1 activators were genetically ablated, we found that expression of “free” Mec1 Activation Domains (MADs) can robustly activate Mec1 and rescue the severe DNA replication and growth defects of these cells back to wild-type levels. However, unlike the activation mediated by endogenous activator-proteins, “free” MADs are unable to stimulate Mec1-mediated suppression of gross chromosomal rearrangements (GCRs), revealing that Mec1’s role in genome maintenance is separable from a previously unappreciated pro-replicative function. Both Mec1’s functions in promoting replication and suppressing GCRs are independent of the downstream checkpoint kinases. Additionally, Mec1-dependent GCR suppression seems to require localized Mec1 action at DNA lesions, which correlates with the phosphorylation of activator-proximal substrates involved in homologous recombination-mediated DNA repair. These findings establish that Mec1 initiates checkpoint signaling, promotes DNA replication, and maintains genetic stability through distinct modes of action.
2019-01-14 | PXD009734 | Pride
Project description:Chromatin replication requires tight coordination of nucleosome assembly machinery with DNA replication machinery. While significant progress has been made in characterizing histone chaperones in this process, the mechanism of whereby nucleosome assembly couples with DNA replication remains largely unknown. Here we show that replication protein A (RPA), a single-stranded DNA (ssDNA) binding protein that is essential for DNA replication provides a binding platform for H3-H4 deposition by histone chaperons and is required for nucleosome formation on nascent chromatin. RPA binds free histone H3-H4 but not nucleosomal histones, and a RPA coated ssDNA stimulates assembly of H3-H4 onto double strand DNA in vitro. RPA mutant with reduced H3-H4 binding exhibits synthetic genetic interaction with mutations at key factors involved in replication-coupled (RC) nucleosome assembly, and are defective in assembly of replicating DNA into nucleosomes in cells. These results reveal a novel function for RPA in nucleosome assembly and a mechanism whereby nucleosome assembly is coordinated with DNA replication.
2017-01-27 | GSE83648 | GEO