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Error-free DNA damage tolerance pathway is facilitated by the Irc5 translocase through cohesin

ABSTRACT: DNA damage tolerance (DDT) mechanisms facilitate replication resumption and completion when DNA replication is blocked by bulky DNA lesions. In budding yeast, template switching (TS) via the Rad18/Rad5 pathway is a favored DDT pathway that involves usage of the sister chromatid as a template to bypass DNA lesions in an error-free recombination-like process. Here, we establish that the Snf2 family translocase Irc5 is a novel factor that promotes TS and averts single-stranded DNA persistence during replication. We demonstrate that during replication stress, Irc5 enables replication progression by assisting enrichment of cohesin complexes, recruited in an Scc2/Scc4-dependent fashion, near blocked replication forks. This allows efficient formation of sister chromatid junctions that are crucial for error-free DNA lesion bypass. Our results support the notion of a key role of cohesin in the completion of DNA synthesis under replication stress, and reveal that the Rad18/Rad5-mediated DDT pathway is linked to cohesin enrichment at sites of perturbed replication via the SNF2 family translocase, Irc5.

SUBMITTER: Dr. Ireneusz, Bernard Litwin

PROVIDER: S-SCDT-EMBOJ-2017-98732 | biostudies-other |

REPOSITORIES: biostudies-other

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Error-free DNA damage tolerance pathway is facilitated by the Irc5 translocase through cohesin.

Project description:DNA damage tolerance (DDT) mechanisms facilitate replication resumption and completion when DNA replication is blocked by bulky DNA lesions. In budding yeast, template switching (TS) via the Rad18/Rad5 pathway is a favored DDT pathway that involves usage of the sister chromatid as a template to bypass DNA lesions in an error-free recombination-like process. Here, we establish that the Snf2 family translocase Irc5 is a novel factor that promotes TS and averts single-stranded DNA persistence during replication. We demonstrate that, during replication stress, Irc5 enables replication progression by assisting enrichment of cohesin complexes, recruited in an Scc2/Scc4-dependent fashion, near blocked replication forks. This allows efficient formation of sister chromatid junctions that are crucial for error-free DNA lesion bypass. Our results support the notion of a key role of cohesin in the completion of DNA synthesis under replication stress and reveal that the Rad18/Rad5-mediated DDT pathway is linked to cohesin enrichment at sites of perturbed replication via the Snf2 family translocase Irc5.

| S-EPMC6138436 | biostudies-literature

DNA bending facilitates the error-free DNA damage tolerance pathway and upholds genome integrity

Project description:DNA replication is sensitive to damage in the template. To bypass lesions and complete replication, cells activate recombination-mediated (error-free) and translesion synthesis-mediated (error-prone) DNA damage tolerance pathways. Crucial for error-free DNA damage tolerance is template switching, which depends on the formation and resolution of damage-bypass intermediates consisting of sister chromatid junctions. Here we show that a chromatin architectural pathway involving the high mobility group box protein Hmo1 channels replication-associated lesions into the error-free DNA damage tolerance pathway mediated by Rad5 and PCNA polyubiquitylation, while preventing mutagenic bypass and toxic recombination. In the process of template switching, Hmo1 also promotes sister chromatid junction formation predominantly during replication. Its C-terminal tail, implicated in chromatin bending, facilitates the formation of catenations/hemicatenations and mediates the roles of Hmo1 in DNA damage tolerance pathway choice and sister chromatid junction formation. Together, the results suggest that replication-associated topological changes involving the molecular DNA bender, Hmo1, set the stage for dedicated repair reactions that limit errors during replication and impact on genome stability. BrdU and proteins ChIP-chip analyses analysis were carried out as described (Bermejo et al., 2009). Labelled probes were hybridized to Affymetrix S.cerevisiae Tiling 1.0 (P/N 900645) arrays and processed with TAS software.

2014-01-28 | E-GEOD-46260 | biostudies-arrayexpress

DNA bending facilitates the error-free DNA damage tolerance pathway and upholds genome integrity.

| S-EPMC3983681 | biostudies-literature

DNA bending facilitates the error-free DNA damage tolerance pathway and upholds genome integrity

2014-01-28 | GSE46260 | GEO

Error-free DNA damage tolerance and sister chromatid proximity during DNA replication rely on the Pol?/Primase/Ctf4 Complex.

Project description:Chromosomal replication is entwined with DNA damage tolerance (DDT) and chromatin structure establishment via elusive mechanisms. Here we examined how specific replication conditions affecting replisome architecture and repriming impact on DDT. We show that Saccharomyces cerevisiae Pol?/Primase/Ctf4 mutants, proficient in bulk DNA replication, are defective in recombination-mediated damage-bypass by template switching (TS) and have reduced sister chromatid cohesion. The decrease in error-free DDT is accompanied by increased usage of mutagenic DDT, fork reversal, and higher rates of genome rearrangements mediated by faulty strand annealing. Notably, the DDT defects of Pol?/Primase/Ctf4 mutants are not the consequence of increased sister chromatid distance, but are instead caused by altered single-stranded DNA metabolism and abnormal replication fork topology. We propose that error-free TS is driven by timely replicative helicase-coupled re-priming. Defects in this event impact on replication fork architecture and sister chromatid proximity, and represent a frequent source of chromosome lesions upon replication dysfunctions.

| S-EPMC4352764 | biostudies-literature

A Unique B-Family DNA Polymerase Facilitating Error-Prone DNA Damage Tolerance in Crenarchaeota.

Project description:Sulfolobus islandicus codes for four DNA polymerases: three are of the B-family (Dpo1, Dpo2, and Dpo3), and one is of the Y-family (Dpo4). Western analysis revealed that among the four polymerases, only Dpo2 exhibited DNA damage-inducible expression. To investigate how these DNA polymerases could contribute to DNA damage tolerance in S. islandicus, we conducted genetic analysis of their encoding genes in this archaeon. Plasmid-borne gene expression revealed that Dpo2 increases cell survival upon DNA damage at the expense of mutagenesis. Gene deletion studies showed although dpo1 is essential, the remaining three genes are dispensable. Furthermore, although Dpo4 functions in housekeeping translesion DNA synthesis (TLS), Dpo2, a B-family DNA polymerase once predicted to be inactive, functions as a damage-inducible TLS enzyme solely responsible for targeted mutagenesis, facilitating GC to AT/TA conversions in the process. Together, our data indicate that Dpo2 is the main DNA polymerase responsible for DNA damage tolerance and is the primary source of targeted mutagenesis. Given that crenarchaea encoding a Dpo2 also have a low-GC composition genome, the Dpo2-dependent DNA repair pathway may be conserved in this archaeal lineage.

| S-EPMC7390963 | biostudies-literature

Mechanism of Error-Free DNA Replication Past Lucidin-Derived DNA Damage by Human DNA Polymerase ?.

Project description:DNA damage impinges on genetic information flow and has significant implications in human disease and aging. Lucidin-3-O-primeveroside (LuP) is an anthraquinone derivative present in madder root, which has been used as a coloring agent and food additive. LuP can be metabolically converted to genotoxic compound lucidin, which subsequently forms lucidin-specific N2-2'-deoxyguanosine (N2-dG) and N6-2'-deoxyadenosine (N6-dA) DNA adducts. Lucidin is mutagenic and carcinogenic in rodents but has low carcinogenic risks in humans. To understand the molecular mechanism of low carcinogenicity of lucidin in humans, we performed DNA replication assays using site-specifically modified oligodeoxynucleotides containing a structural analogue (LdG) of lucidin-N2-dG DNA adduct and determined the crystal structures of DNA polymerase (pol) ? in complex with LdG-bearing DNA and an incoming nucleotide. We examined four human pols (pol ?, pol ?, pol ?, and Rev1) in their efficiency and accuracy during DNA replication with LdG; these pols are key players in translesion DNA synthesis. Our results demonstrate that pol ? efficiently and accurately replicates past the LdG adduct, whereas DNA replication by pol ?, pol ? is compromised to different extents. Rev1 retains its ability to incorporate dCTP opposite the lesion albeit with decreased efficiency. Two ternary crystal structures of pol ? illustrate that the LdG adduct is accommodated by pol ? at the enzyme active site during insertion and postlesion-extension steps. The unique open active site of pol ? allows the adducted DNA to adopt a standard B-form for accurate DNA replication. Collectively, these biochemical and structural data provide mechanistic insights into the low carcinogenic risk of lucidin in humans.

| S-EPMC5696069 | biostudies-literature

Error-free and error-prone DNA repair gene expression through reprogramming and passage in human iPS cells

Project description:Medical applications of human iPS cells(hiPSC) are evolving, but detailed elucidation of the mechanisms of reprogramming remains to be elucidated. Reprogramming is accompanied by an increase in the expression of related genes that maintain pluripotency, such as OCT3 /4 and NANOG. Also, through reprogramming, many CNVs and point mutation arise in genomes, which constitute a major barrier to the use of hiPSC for regenerative medicine. On the other hand, we recently found that DNA repair-related genes expression are altered through reprogramming, elevated expression of genes that accurately convey genomic information, such as homologous recombination (HR) and mismatch repair(MMR), and decreased expression of error-prone translesion Synthesis polymerase(TLS). Here, we confirmed this expression change in another cell-line, and further found that this expression change was maintained by overlapping passages as well as OCT3 /4 and NANOG. This suggests that changes in the expression of DNA repair-related genes associated with reprogramming and their maintenance may be new indicators of the quality control of cells exhibiting pluripotency.

2019-07-21 | GSE134441 | GEO

DNA Damage Tolerance Pathway Choice Through Uls1 Modulation of Srs2 SUMOylation in <i>Saccharomyces cerevisiae</i>.

Project description:DNA damage tolerance and homologous recombination pathways function to bypass replication-blocking lesions and ensure completion of DNA replication. However, inappropriate activation of these pathways may lead to increased mutagenesis or formation of deleterious recombination intermediates, often leading to cell death or cancer formation in higher organisms. Post-translational modifications of PCNA regulate the choice of repair pathways at replication forks. Its monoubiquitination favors translesion synthesis, while polyubiquitination stimulates template switching. Srs2 helicase binds to small ubiquitin-related modifier (SUMO)-modified PCNA to suppress a subset of Rad51-dependent homologous recombination. Conversely, SUMOylation of Srs2 attenuates its interaction with PCNA Sgs1 helicase and Mus81 endonuclease are crucial for disentanglement of repair intermediates at the replication fork. Deletion of both genes is lethal and can be rescued by inactivation of Rad51-dependent homologous recombination. Here we show that Saccharomyces cerevisiae Uls1, a member of the Swi2/Snf2 family of ATPases and a SUMO-targeted ubiquitin ligase, physically interacts with both PCNA and Srs2, and promotes Srs2 binding to PCNA by downregulating Srs2-SUMO levels at replication forks. We also identify deletion of ULS1 as a suppressor of mus81Δ sgs1Δ synthetic lethality and hypothesize that uls1Δ mutation results in a partial inactivation of the homologous recombination pathway, detrimental in cells devoid of both Sgs1 and Mus81 We thus propose that Uls1 contributes to the pathway where intermediates generated at replication forks are dismantled by Srs2 bound to SUMO-PCNA. Upon ULS1 deletion, accumulating Srs2-SUMO-unable to bind PCNA-takes part in an alternative PCNA-independent recombination repair salvage pathway(s).

| S-EPMC5419492 | biostudies-literature

Cohesin Causes Replicative DNA Damage by Trapping DNA Topological Stress.

Project description:DNA topological stress inhibits DNA replication fork (RF) progression and contributes to DNA replication stress. In Saccharomyces cerevisiae, we demonstrate that centromeric DNA and the rDNA array are especially vulnerable to DNA topological stress during replication. The activity of the SMC complexes cohesin and condensin are linked to both the generation and repair of DNA topological-stress-linked damage in these regions. At cohesin-enriched centromeres, cohesin activity causes the accumulation of DNA damage, RF rotation, and pre-catenation, confirming that cohesin-dependent DNA topological stress impacts on normal replication progression. In contrast, at the rDNA, cohesin and condensin activity inhibit the repair of damage caused by DNA topological stress. We propose that, as well as generally acting to ensure faithful genetic inheritance, SMCs can disrupt genome stability by trapping DNA topological stress.

| S-EPMC7242899 | biostudies-literature

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