Identification of<i>Saccharomyces cerevisiae</i>Genes Whose Deletion Causes Synthetic Effects in Cells with Reduced Levels of the Nuclear Pif1 DNA Helicase

Stundon, Jennifer; Zakian, Virginia A.

doi:10.1534/g3.115.021139

Cited by 11 publications

(16 citation statements)

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“…Therefore, if ScPif1 contributes to a function that is important for the segregation of centromeres, it must share this function with another protein, perhaps a helicase, other than Rrm3. However, a synthetic screen to identify nonessential genes that are synthetically lethal or sick in a pif1-m2 background did not identify any of the over 100 nonessential genes that have helicase motifs (Stundon and Zakian 2015). We suggest from the cell cycle pattern of Rrm3 binding in pif1-m2 cells (Figure 3, A, C, and E) that Rrm3 might carry out the late cell cycle activity of ScPif1 in pif1-m2 cells.…”

Section: Discussionmentioning

confidence: 99%

“…However, rrm3 Δ pif1-m2 cells are benomyl- and nocodazole-resistant (Figure 6A and Figure S3), which is not expected if the two helicases cooperate to promote sister chromatid separation. One interaction that came out of the pif1-m2 synthetic screen (Stundon and Zakian 2015) that might be relevant to a post-S phase function for ScPif1 at centromeres was the lethality of pif1-m2 cdh1 Δ cells. Cdh1 is an activator of the APC (anaphase-promoting complex) that drives cells into anaphase, in part by leading to the release of cohesin from the centromeres of sister chromatids (Biggins 2013).…”

Section: Discussionmentioning

confidence: 99%

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Two Pif1 Family DNA Helicases Cooperate in Centromere Replication and Segregation in Saccharomyces cerevisiae

et al. 2018

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Pif1 family helicases are found in virtually all eukaryotes. Saccharomyces cerevisiae (Sc) encodes two Pif1 family helicases, ScPif1 and Rrm3. ScPif1 is multifunctional, required not only for maintenance of mitochondrial DNA but also for multiple distinct nuclear functions. Rrm3 moves with the replication fork and promotes movement of the fork through ∼1400 hard-to-replicate sites, including centromeres. Here we show that ScPif1, like Rrm3, bound robustly to yeast centromeres but only if the centromere was active. While Rrm3 binding to centromeres occurred in early to mid S phase, about the same time as centromere replication, ScPif1 binding occurred later in the cell cycle when replication of most centromeres is complete. However, the timing of Rrm3 and ScPif1 centromere binding was altered by the absence of the other helicase, such that Rrm3 centromere binding occurred later in pif1-m2 cells and ScPif1 centromere binding occurred earlier in rrm3Δ cells. As shown previously, the modest pausing of replication forks at centromeres seen in wild-type cells was increased in the absence of Rrm3. While a lack of ScPif1 did not result in increased fork pausing at centromeres, pausing was even higher in rrm3Δ pif1Δ cells than in rrm3Δ cells. Likewise, centromere function as monitored by the loss rate of a centromere plasmid was increased in rrm3Δ but not pif1Δ cells, and was even higher in rrm3Δ pif1Δ cells than in rrm3Δ cells. Thus, ScPif1 promotes centromere replication and segregation, but only in the absence of Rrm3. These data also hint at a potential post-S phase function for ScPif1 at centromeres. These studies add to the growing list of ScPif1 functions that promote chromosome stability.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Two Pif1 Family DNA Helicases Cooperate in Centromere Replication and Segregation in Saccharomyces cerevisiae

et al. 2018

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“…Sgs1 is likely to operate in at least a partially redundant role with non-RecQ DNA helicases including SRS2 (already implicated in the intra-S phase DNA damage checkpoint) and the 5' to 3' DNA helicase RRM3, as shown by synthetic lethality analyses by microarray (SLAM), a novel experimental approach at the time [266]. Since then, many papers describing synthetic lethal interactions of DNA helicases have appeared in the literature suggesting a general theme that helicases respond to replication stress via extended networks with numerous genetic interactions (for examples, see [267][268][269][270]). The recent identification of WRN helicase (mutated in Werner syndrome (WS), see below) as a synthetic lethal gene in microsatellite unstable cancers with defects in DNA MMR genes emphasizes the point [271][272][273][274].…”

Section: Replication Stressmentioning

confidence: 99%

History of DNA Helicases

Brosh

Matson

2020

Genes

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Since the discovery of the DNA double helix, there has been a fascination in understanding the molecular mechanisms and cellular processes that account for: (i) the transmission of genetic information from one generation to the next and (ii) the remarkable stability of the genome. Nucleic acid biologists have endeavored to unravel the mysteries of DNA not only to understand the processes of DNA replication, repair, recombination, and transcription but to also characterize the underlying basis of genetic diseases characterized by chromosomal instability. Perhaps unexpectedly at first, DNA helicases have arisen as a key class of enzymes to study in this latter capacity. From the first discovery of ATP-dependent DNA unwinding enzymes in the mid 1970’s to the burgeoning of helicase-dependent pathways found to be prevalent in all kingdoms of life, the story of scientific discovery in helicase research is rich and informative. Over four decades after their discovery, we take this opportunity to provide a history of DNA helicases. No doubt, many chapters are left to be written. Nonetheless, at this juncture we are privileged to share our perspective on the DNA helicase field – where it has been, its current state, and where it is headed.

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“…Null def1 mutants exhibit diverse phenotypes, including slow growth [2], defective cytokinesis and meiosis [3], abnormal cell size [4] and increased sensitivity to mutagens [3]. DEF1 is involved in genome stability control: def1Δ is synthetically sick with mutations in the PIF1 gene encoding for DNA helicase that participates in DNA maintenance and replication associated with DNA breaks [5, 6]; Def1 is found at sites of double strand breaks [7]; Def1 assists repair of abasic sites on the transcribed strands [8].…”

Section: Introductionmentioning

confidence: 99%

Deletion of the DEF1 gene does not confer UV-immutability but frequently leads to self-diploidization in yeast Saccharomyces cerevisiae

2018

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In yeast Saccharomyces cerevisiae, the DEF1 gene is responsible for regulation of many cellular processes including ubiquitin-dependent degradation of DNA metabolism proteins. Recently it has been proposed that Def1 promotes degradation of the catalytic subunit of DNA polymerase δ at sites of DNA damage and regulates a switch to specialized polymerases and, as a consequence, DNA-damage induced mutagenesis. The idea was based substantially on the severe defects in induced mutagenesis observed in the def1 mutants. We describe that UV mutability of def1Δ strains is actually only moderately affected, while the virtual absence of UV mutagenesis in many def1Δ clones is caused by a novel phenotype of the def1 mutants, proneness to self-diploidization. Diploids are extremely frequent (90%) after transformation of wild-type haploids with def1::kanMX disruption cassette and are frequent (2.3%) in vegetative haploid def1 cultures. Such diploids look "UV immutable" when assayed for recessive forward mutations but have normal UV mutability when assayed for dominant reverse mutations. The propensity for frequent self-diploidization in def1Δ mutants should be taken into account in studies of the def1Δ effect on mutagenesis. The true haploids with def1Δ mutation are moderately UV sensitive but retain substantial UV mutagenesis for forward mutations: they are fully proficient at lower doses and only partially defective at higher doses of UV. We conclude that Def1 does not play a critical role in damage-induced mutagenesis.

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Identification ofSaccharomyces cerevisiaeGenes Whose Deletion Causes Synthetic Effects in Cells with Reduced Levels of the Nuclear Pif1 DNA Helicase

Cited by 11 publications

References 71 publications

Two Pif1 Family DNA Helicases Cooperate in Centromere Replication and Segregation in Saccharomyces cerevisiae

Two Pif1 Family DNA Helicases Cooperate in Centromere Replication and Segregation in Saccharomyces cerevisiae

History of DNA Helicases

Deletion of the DEF1 gene does not confer UV-immutability but frequently leads to self-diploidization in yeast Saccharomyces cerevisiae

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