MRX protects fork integrity at protein–DNA barriers, and its absence causes checkpoint activation dependent on chromatin context

Bentsen, Iben Bach; Nielsen, Ida; Lisby, Michael; Nielsen, Helena Breth; Gupta, Souvik Sen; Mundbjerg, Kamilla; Andersen, Anders H.; Bjergbæk, Lotte

doi:10.1093/nar/gkt051

Cited by 18 publications

(19 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Increased numbers of stalled replication forks might therefore compromise cell viability. Consistent with this idea, elevating the strength of RFBs, either by removal of the Rrm3 helicase or by overexpression of Fob1, leads to synthetic sickness in combination with disruption of the MRX complex [15–17], probably due to a role for MRX in fork repair [50], fork restart [20], or fork stabilization at RFBs [17]. …”

Section: Resultsmentioning

confidence: 99%

“…Consistent with this idea, genome-wide accentuation of RFBs in rrm3Δ cells leads to fork collapse and breakage, and to loss of viability in combination with mutation of DNA repair genes such as MRE11 , SGS1 , and SRS2 [15, 16]. Similarly, specific strengthening of the rDNA RFB by Fob1 overexpression decreases viability in mre11Δ mutants [17]. Apart from its conserved function in DNA double strand break (DSB) nucleolytic processing (resection) [18] the MRX complex (Mre11, Rad50 and Xrs2) also participates in replication fork stabilization under conditions of replication stress (e.g.…”

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

Budding Yeast Rif1 Controls Genome Integrity by Inhibiting rDNA Replication

et al. 2016

View full text Add to dashboard Cite

The Rif1 protein is a negative regulator of DNA replication initiation in eukaryotes. Here we show that budding yeast Rif1 inhibits DNA replication initiation at the rDNA locus. Absence of Rif1, or disruption of its interaction with PP1/Glc7 phosphatase, leads to more intensive rDNA replication. The effect of Rif1-Glc7 on rDNA replication is similar to that of the Sir2 deacetylase, and the two would appear to act in the same pathway, since the rif1Δ sir2Δ double mutant shows no further increase in rDNA replication. Loss of Rif1-Glc7 activity is also accompanied by an increase in rDNA repeat instability that again is not additive with the effect of sir2Δ. We find, in addition, that the viability of rif1Δ cells is severely compromised in combination with disruption of the MRX or Ctf4-Mms22 complexes, both of which are implicated in stabilization of stalled replication forks. Significantly, we show that removal of the rDNA replication fork barrier (RFB) protein Fob1, alleviation of replisome pausing by deletion of the Tof1/Csm3 complex, or a large deletion of the rDNA repeat array all rescue this synthetic growth defect of rif1Δ cells lacking in addition either MRX or Ctf4-Mms22 activity. These data suggest that the repression of origin activation by Rif1-Glc7 is important to avoid the deleterious accumulation of stalled replication forks at the rDNA RFB, which become lethal when fork stability is compromised. Finally, we show that Rif1-Glc7, unlike Sir2, has an important effect on origin firing outside of the rDNA locus that serves to prevent activation of the DNA replication checkpoint. Our results thus provide insights into a mechanism of replication control within a large repetitive chromosomal domain and its importance for the maintenance of genome stability. These findings may have important implications for metazoans, where large blocks of repetitive sequences are much more common.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Budding Yeast Rif1 Controls Genome Integrity by Inhibiting rDNA Replication

et al. 2016

View full text Add to dashboard Cite

show abstract

“…The observation that mre11⌬, rad50⌬, and xrs2⌬ mutations but not rad51⌬ and rad52⌬ muta- tions caused increased GCR rates when combined with an rnh203⌬ mutation could reflect the role of Mre11-Rad50-Xrs2 but not Rad51 or Rad52 in stabilizing and processing stalled replication forks (97,98). Similarly, Sgs1, Esc2, Esc4/Rtt107, the Mus81-Mms4 complex, and the sumoylation of PCNA, which is blocked by the pol30-119 mutation, play roles in the processing of stalled replication forks (69,76,80,87).…”

Section: Discussionmentioning

confidence: 99%

A Saccharomyces cerevisiae RNase H2 Interaction Network Functions To Suppress Genome Instability

Allen-Soltero

Martı́nez

Putnam

et al. 2014

Molecular and Cellular Biology

View full text Add to dashboard Cite

Errors during DNA replication are one likely cause of gross chromosomal rearrangements (GCRs). Here, we analyze the role of RNase H2, which functions to process Okazaki fragments, degrade transcription intermediates, and repair misincorporated ribonucleotides, in preventing genome instability. The results demonstrate that rnh203 mutations result in a weak mutator phenotype and cause growth defects and synergistic increases in GCR rates when combined with mutations affecting other DNA metabolism pathways, including homologous recombination (HR), sister chromatid HR, resolution of branched HR intermediates, postreplication repair, sumoylation in response to DNA damage, and chromatin assembly. In some cases, a mutation in RAD51 or TOP1 suppressed the increased GCR rates and/or the growth defects of rnh203⌬ double mutants. This analysis suggests that cells with RNase H2 defects have increased levels of DNA damage and depend on other pathways of DNA metabolism to overcome the deleterious effects of this DNA damage.

show abstract

“…In fact, Mre11 has been proposed to tether two DNA strands together, independent of DSB formation (29). Moreover, in Saccharomyces cerevisiae, the MRX (Mre11/Rad50/Xrs2) complex protects replication fork integrity by preventing ssDNA accumulation at replication barriers (50). Hence, Rad51 and Mre11 depletion might favor ssDNA accumulation at the end of replication forks and subsequent repriming.…”

Section: Rad51 Prevents Dysregulated Fork Elongation After Uv Irradiamentioning

confidence: 99%

Rad51 recombinase prevents Mre11 nuclease-dependent degradation and excessive PrimPol-mediated elongation of nascent DNA after UV irradiation

Vallerga

Mansilla

Federico

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

After UV irradiation, DNA polymerases specialized in translesion DNA synthesis (TLS) aid DNA replication. However, it is unclear whether other mechanisms also facilitate the elongation of UVdamaged DNA. We wondered if Rad51 recombinase (Rad51), a factor that escorts replication forks, aids replication across UV lesions. We found that depletion of Rad51 impairs S-phase progression and increases cell death after UV irradiation. Interestingly, Rad51 and the TLS polymerase polη modulate the elongation of nascent DNA in different ways, suggesting that DNA elongation after UV irradiation does not exclusively rely on TLS events. In particular, Rad51 protects the DNA synthesized immediately before UV irradiation from degradation and avoids excessive elongation of nascent DNA after UV irradiation. In Rad51-depleted samples, the degradation of DNA was limited to the first minutes after UV irradiation and required the exonuclease activity of the double strand break repair nuclease (Mre11). The persistent dysregulation of nascent DNA elongation after Rad51 knockdown required Mre11, but not its exonuclease activity, and PrimPol, a DNA polymerase with primase activity. By showing a crucial contribution of Rad51 to the synthesis of nascent DNA, our results reveal an unanticipated complexity in the regulation of DNA elongation across UV-damaged templates.PrimPol | polκ | polη | DNA damage tolerance | DNA replication T he DNA-binding protein Rad51 is a central component of homologous recombination repair (HRR). HRR repairs doublestrand breaks (DSBs) in an error-free way and processes one-ended DSBs to reactivate collapsed replication forks (1). During HRR, DSBs are processed by the 3′-to-5′ exonuclease activity of the double strand break repair nuclease (Mre11) to generate protruding 3′ ssDNA at DSBs. The ssDNA is then coated with Rad51, a factor that catalyzes homology search and strand invasion. The loading and stabilization of Rad51/ssDNA complexes are supported by multiple mediators, such as the tumor suppressor BRCA2 (breast cancer 2) (1). Moreover, Rad51 promotes XPF1-and Exo1-mediated DSB formation after gemcitabine-induced irreversible ribonucleotide reductase inhibition, thus promoting cell death (2). The signals that redirect Rad51 into a DSB formation pathway rather than DSB repair are not yet known.The functions of Rad51 are not limited to the processing/ generation of DSBs. Over the past few years, it has become evident that Rad51 escorts ongoing replication forks regardless of the presence of DSBs (3-5). Specifically, Rad51 protects persistently stalled replication forks from Mre11-mediated nucleolytic degradation and facilitates replication fork restart when the replication-halting agent hydroxyurea (HU) or aphidicolin (APH) is removed (6-19). Such novel functions of Rad51 require many HRR factors, including BCRA2, FANCD2 (Fanconi Anemia Complementation group protein D2), CtIP, BRCA1, and the WRN helicase, but are independent of HRR effectors, such as Rad54 (6, 7). Rad51-dependent fork-restart and fork-protection ...

show abstract

MRX protects fork integrity at protein–DNA barriers, and its absence causes checkpoint activation dependent on chromatin context

Cited by 18 publications

References 59 publications

Budding Yeast Rif1 Controls Genome Integrity by Inhibiting rDNA Replication

Budding Yeast Rif1 Controls Genome Integrity by Inhibiting rDNA Replication

A Saccharomyces cerevisiae RNase H2 Interaction Network Functions To Suppress Genome Instability

Rad51 recombinase prevents Mre11 nuclease-dependent degradation and excessive PrimPol-mediated elongation of nascent DNA after UV irradiation

Contact Info

Product

Resources

About