Rad53 checkpoint kinase couples leading and lagging strand DNA synthesis
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ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
PROVIDER: GSE89721 | GEO | 2018/02/11
REPOSITORIES: GEO
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Project description:Rad53 checkpoint kinase couples leading and lagging strand DNA synthesis
| PRJNA352998 | ENA
Project description:Faithful duplication of DNA is essential for the maintenance of genomic stability in all organisms. DNA synthesis proceeds bi-directionally with continuous synthesis of leading strand DNA and discontinuous synthesis of lagging strand DNA. Herein, we describe a method of enriching and Sequencing of Protein-Associated Nascent strand DNA (eSPAN) to detect whether a protein binds the leading- and lagging-strands of DNA replication forks. We show that Pol-epsilon, PCNA, Cdc45, Mcm6 and Mcm10 preferentially associate with leading strands, whereas Pol-alpha, Pol32, Pol-delta, Rfa1 and Rfc1 associate with lagging strands of hydroxyurea (HU)-stalled replication forks. In contrast, PCNA is enriched at lagging strands of normal replication forks in wild type cells and HU-stalled forks in cells lacking Elg1. These studies demonstrate a strategy to reveal proteins at leading and lagging strands of DNA replication forks, and suggest that the unloading of PCNA from lagging strands of HU-stalled replication forks helps maintain genome integrity. We synchronized yeast cells at G1 and released into early S phase in the presence of BrdU, a nucleotide analog that can be incorporated into newly synthesized DNA strand, and hydroxyurea (HU), a ribonucleotide reductase inhibitor. HU has no effect on initiation of DNA replication at early replication origins, but inhibit late replication firing. In addition, replication forks are stalled due to depletion of dNTPs. We then performed chromatin-immunoprecipitation of 12 proteins of interest following a standard procedure. Protein-bound DNAs were then reverse-crosslinked and double strand DNA was denatured. Nascent DNA was enriched by immunoprecipitation using anti-BrdU antibodies. The recovered ssDNA was first marked with ligation to one oligo at 3M-bM-^@M-^Y end before conversion to dsDNA for library preparation and sequencing. In this way, the directionality of ssDNA and therefore strand information of each sequenced DNA were known. The sequencing tag was mapped to both Watson (red) and Crick (blue) strands of the reference genome. In addition to ChIP-eSPAN, we also performed BrdU-IP and single strand DNA sequence (BrdU-ssSeq) and protein ChIP followed by single-strand DNA sequencing (ChIP-ssSeq) for each corresponding ChIP-eSPAN experiment. We also performed Mcm4 and Mcm6 ChIP-seq using cells synchronized at G1 phase of the cell cycle for identification of replication origins in comparison with published dataset. Some protein ChIP-ssSeq and ChIP-eSPAN experiments were repeated and the data fits well each other. Therefore, we did not repeat all protein ChIP-ssSeq and ChIP-eSPAN experiments.
2014-10-29 | E-GEOD-52614 | biostudies-arrayexpress
Project description:We have developed a method to analyze single-stranded DNA (ssDNA) formation on a genomic scale by using microarrays. Using this technique we have assessed the location and the amount of ssDNA in S. cerevisiae during DNA replication. We have observed that when replication is impeded by hydroxyurea, ssDNA formation can be detected in both wild type and the checkpoint-deficient rad53 cells. However, while wild type cells showed ssDNA formation at only a subset of origins, rad53 cells formed ssDNA at virtually all known origins. Moreover, in rad53 cells the ssDNA regions did not expand over time, presumably due to collapsed replication forks. We also applied this method to map origins in S. pombe, taking advantage of the conserved replication checkpoint function by Cds1, the homolog of Rad53 in S. pombe. Keywords: ssDNA, HU, replication, time course
2006-01-30 | GSE4099 | GEO
Project description:Faithful duplication of DNA is essential for the maintenance of genomic stability in all organisms. DNA synthesis proceeds bi-directionally with continuous synthesis of leading strand DNA and discontinuous synthesis of lagging strand DNA. Herein, we describe a method of enriching and Sequencing of Protein-Associated Nascent strand DNA (eSPAN) to detect whether a protein binds the leading- and lagging-strands of DNA replication forks. We show that Pol-epsilon, PCNA, Cdc45, Mcm6 and Mcm10 preferentially associate with leading strands, whereas Pol-alpha, Pol32, Pol-delta, Rfa1 and Rfc1 associate with lagging strands of hydroxyurea (HU)-stalled replication forks. In contrast, PCNA is enriched at lagging strands of normal replication forks in wild type cells and HU-stalled forks in cells lacking Elg1. These studies demonstrate a strategy to reveal proteins at leading and lagging strands of DNA replication forks, and suggest that the unloading of PCNA from lagging strands of HU-stalled replication forks helps maintain genome integrity.
2014-10-29 | GSE52614 | GEO
Project description:Replication stress activates the Mec1ATR and Rad53 kinases. Rad53 phosphorylates nuclear pores to counteract gene gating, thus preventing aberrant transitions at forks approaching transcribed genes. Here, we show that Rrm3 and Pif1, DNA helicases assisting fork progression across pausing sites, are detrimental in rad53 mutants experiencing replication stress. Rrm3 and Pif1 ablations rescue cell lethality, chromosome fragmentation, replisome-fork dissociation, fork reversal, and processing in rad53 cells. Through phosphorylation, Rad53 regulates Rrm3 and Pif1; phospho-mimicking rrm3 mutants ameliorate rad53 phenotypes following replication stress without affecting replication across pausing elements under normal conditions. Hence, the Mec1-Rad53 axis protects fork stability by regulating nuclear pores and DNA helicases. We propose that following replication stress, forks stall in an asymmetric conformation by inhibiting Rrm3 and Pif1, thus impeding lagging strand extension and preventing fork reversal; conversely, under unperturbed conditions, the peculiar conformation of forks encountering pausing sites would depend on active Rrm3 and Pif1. BrdU incorporation profiles by ssDNA-BrdU IP on chip have been generated as described (Katou et al., 2003). Protein binding profiles by ChIP-chip analysis were generated as described (Bermejo et al., 2009). Labeled probes were hybridized to Affymetrix S.cerevisiae Tiling 1.0 (P/N 900645) arrays and processed with TAS software.
2015-09-24 | E-GEOD-68214 | biostudies-arrayexpress
Project description:DNA polymerase delta (Pol ∂) plays several essential roles in eukaryotic DNA replication and repair. At the replication fork, Pol ∂ is responsible for the synthesis and processing of the lagging strand; this role requires Pol ∂ to extend Okazaki fragment primers synthesized by Pol ⍺-primase, and to carry out strand-displacement synthesis coupled to nuclease cleavage during Okazaki fragment termination. Destabilizing mutations in human Pol ∂ subunits cause replication stress and syndromic immunodeficiency. Analogously, reduced levels of Pol ∂ in Saccharomyces cerevisiae lead to pervasive genome instability. Here, we analyze the how the depletion of Pol ∂ impacts replication initiation and elongation in vivo in S. cerevisiae. We determine that Pol ∂ depletion leads to a dependence on checkpoint signaling and recombination-mediated repair for cellular viability. By analyzing nascent lagging-strand products, we observe both a genome-wide change in the establishment and progression of replication forks and a global defect in Pol ∂-mediated Okazaki fragment processing. Additionally, we detect significant lagging-strand synthesis by the leading-strand polymerase (Pol ɛ) in late regions of the genome when Pol ∂ is depleted.
2019-12-13 | GSE141884 | GEO
Project description:Prior to ligation, each Okazaki fragment synthesized on the lagging strand in eukaryotes must be nucleolytically processed. Nuclease cleavage takes place in the context of 5’ flap structures generated via strand-displacement synthesis by DNA polymerase delta. At least three DNA nucleases: Rad27 (Fen1), Dna2, and Exo1, have been implicated in processing Okazaki fragment flaps. However, neither the contributions of individual nucleases to lagging-strand synthesis nor the structure of the DNA intermediates formed in their absence have been clearly defined in vivo. By conditionally depleting lagging-strand nucleases and directly analyzing Okazaki fragments synthesized in vivo in S. cerevisiae, we conduct a systematic evaluation of the impact of Rad27, Dna2 and Exo1 on lagging-strand synthesis. We find that Rad27 processes the majority of lagging-strand flaps, with a significant additional contribution from Exo1 but not from Dna2. When nuclease cleavage is impaired, we observe a reduction in strand-displacement synthesis as opposed to the widespread generation of long Okazaki fragment 5’ flaps, as predicted by some models. Further, using cyclin-controlled constructs, we demonstrate that both the nucleolytic processing and the ligation of Okazaki fragments can be uncoupled from DNA replication and delayed until after synthesis of the majority of the genome is complete.
2018-08-04 | GSE118078 | GEO
Project description:The DNA damage checkpoint senses the presence of DNA lesions and controls the cellular response thereto. A crucial DNA damage signal is single-stranded DNA (ssDNA), which is frequently found at sites of DNA damage and recruits the sensor checkpoint kinase Mec1-Ddc2. However, how this signal – and therefore the cells’ DNA damage load – is quantified, is poorly understood. Here, we use genetic manipulation of DNA end resection at a site-specific DNA double-strand break (DSB) in budding yeast to generate quantitatively different DNA damage (ssDNA) signals. Interestingly, two major targets of the Mec1-Ddc2 kinase – Rad53 and γH2A – differ in their response to the ssDNA signal, indicating distinct signalling circuits within the checkpoint. The local checkpoint signalling circuit leading to γH2A phosphorylation is non-quantitative and unresponsive to increased amounts of damage-associated Mec1-Ddc2 kinase. In contrast, the global checkpoint signalling circuit, which triggers Rad53 activation, integrates the ssDNA signal quantitatively. We find that not only Mec1-Ddc2 association, but also loading of the 9-1-1 co-sensor complex is enhanced during ongoing resection. Moreover, we can uncouple global checkpoint activation from the amount of Mec1-Ddc2 kinase at the lesion by using mutant conditions that hyper-activate the 9-1-1 signalling axis and at the same time show reduced amounts of damage-associated Mec1-Ddc2 kinase. We therefore propose that a key function of the 9-1-1 complex and the downstream checkpoint mediators is to generate a checkpoint response, which is quantitative and proportional to the cellular DNA damage load. The DNA damage checkpoint senses the presence of DNA lesions and controls the cellular response thereto. A crucial DNA damage signal is single-stranded DNA (ssDNA), which is frequently found at sites of DNA damage and recruits the sensor checkpoint kinase Mec1-Ddc2. However, how this signal – and therefore the cells’ DNA damage load – is quantified, is poorly understood. Here, we use genetic manipulation of DNA end resection at a site-specific DNA double-strand break (DSB) in budding yeast to generate quantitatively different DNA damage (ssDNA) signals. Interestingly, two major targets of the Mec1-Ddc2 kinase – Rad53 and γH2A – differ in their response to the ssDNA signal, indicating distinct signalling circuits within the checkpoint. The local checkpoint signalling circuit leading to γH2A phosphorylation is non-quantitative and unresponsive to increased amounts of damage-associated Mec1-Ddc2 kinase. In contrast, the global checkpoint signalling circuit, which triggers Rad53 activation, integrates the ssDNA signal quantitatively. We find that not only Mec1-Ddc2 association, but also loading of the 9-1-1 co-sensor complex is enhanced during ongoing resection. Moreover, we can uncouple global checkpoint activation from the amount of Mec1-Ddc2 kinase at the lesion by using mutant conditions that hyper-activate the 9-1-1 signalling axis and at the same time show reduced amounts of damage-associated Mec1-Ddc2 kinase. We therefore propose that a key function of the 9-1-1 complex and the downstream checkpoint mediators is to generate a checkpoint response, which is quantitative and proportional to the cellular DNA damage load.
2019-01-12 | GSE124948 | GEO
Project description:In many mammalian tissues and cells, two classes of mitochondrial DNA (mtDNA) replication intermediates have been observed. One involves leading-strand synthesis in the absence of synchronous lagging-strand synthesis (strand-asynchronous replication), and the other has properties of coupled leading- and lagging-strand synthesis (strand-coupled replication). While strand-asynchronous replication is primed by long RNA synthesized from a defined transcription initiation site, little is known about the commencement of strand-coupled replication. To investigate it, we attempted to abolish strand-asynchronous replication in cultured human cybrid cells by knocking out the components of the transcription initiation complexes, mitochondrial transcription factor B2 (TFB2M/mtTFB2) and mitochondrial RNA polymerase (POLRMT/mtRNAP). Surprisingly, removal of either protein resulted in the complete mtDNA loss, demonstrating for the first time that TFB2M and POLRMT are indispensable for human mtDNA maintenance. Moreover, the lack of TFB2M could not be compensated for by mitochondrial transcription factor B1 (TFB1M/mtTFB1). These findings indicate that TFB2M and POLRMT are crucial for the priming of not only strand-asynchronous but also strand-coupled replication, providing deeper insights into the molecular basis of strand-coupled replication initiation.
2021-11-21 | GSE161542 | GEO
Project description:During every cell cycle, both the genome and the associated chromatin must be accurately replicated. Chromatin Assembly Factor-1 (CAF-1) is a key regulator of chromatin replication, but how CAF-1 functions in relation to the DNA replication machinery is unknown. Here, we reveal that this crosstalk differs between the leading and lagging strand at replication forks. Using biochemical reconstitution, we show that DNA and histones promote CAF-1 recruitment to its binding partner PCNA and reveal that two CAF-1 complexes are required for efficient nucleosome assembly under these conditions. Remarkably, in the context of the replisome, CAF-1 competes with the leading strand DNA polymerase epsilon (Pole) for PCNA binding. However, CAF-1 does not affect the activity of the lagging strand DNA polymerase Delta (Pold). Yet, in cells, CAF-1 deposits newly synthesized histones equally on both daughter strands. Thus, on the leading strand, chromatin assembly by CAF-1 cannot occur simultaneously to DNA synthesis, while on the lagging strand these processes may be coupled. We propose that these differences may facilitate distinct parental histone recycling mechanisms and accommodate the inherent asymmetry of DNA replication.
2023-08-08 | GSE223782 | GEO