Nuclease activity of
            <i>Saccharomyces cerevisiae</i>
            Dna2 inhibits its potent DNA helicase activity

Levikova, Maryna; Klaue, Daniel; Seidel, Ralf; Ćejka, Petr

doi:10.1073/pnas.1300390110

Cited by 55 publications

(128 citation statements)

References 53 publications

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“…The physiological role of the Dna2 helicase is not yet clear. The DNA unwinding activity of Dna2 is vigorous, comparable with the helicase capacity of Sgs1, yet it is cryptic and only becomes apparent upon inactivation of the Dna2 nuclease (79). It is tempting to think that the helicase of Dna2 functions in concert with that of Sgs1 (28).…”

Section: Sgs1-dna2 Resection Pathwaymentioning

confidence: 99%

DNA End Resection: Nucleases Team Up with the Right Partners to Initiate Homologous Recombination

Ćejka

2015

Journal of Biological Chemistry

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The repair of DNA double-strand breaks by homologous recombination commences by nucleolytic degradation of the 5-terminated strand of the DNA break. This leads to the formation of 3-tailed DNA, which serves as a substrate for the strand exchange protein Rad51. The nucleoprotein filament then invades homologous DNA to drive template-directed repair. In this review, I discuss mainly the mechanisms of DNA end resection in Saccharomyces cerevisiae, which includes short-range resection by Mre11-Rad50-Xrs2 and Sae2, as well as processive long-range resection by Sgs1-Dna2 or Exo1 pathways. Resection mechanisms are highly conserved between yeast and humans, and analogous machineries are found in prokaryotes as well. Homologous recombination (HR)2 plays a central role in the repair of DNA double-strand breaks (DSBs) (1). In vegetative cells, recombination restores broken DNA to preserve genome integrity. In meiosis, HR promotes proper chromosome segregation and exchange of genetic information between maternal and paternal genomes, and thus contributes to the generation of genetic diversity. Recombination is initiated upon the formation of ssDNA overhangs through a process termed DNA end resection. The nucleolytic processing of broken DNA ends is essential for all recombination mechanisms (Fig. 1). Resection of DSBs commits their repair to HR as it prevents ligation by the potentially more mutagenic non-homologous end-joining (NHEJ) pathway (2-4). Resected DNA is first coated by the ssDNA-binding protein replication protein A (RPA). In most cases, RPA is subsequently replaced with the strand exchange protein Rad51, forming a nucleoprotein filament capable of invading homologous DNA. Repair can then proceed via either of two main recombination pathways, synthesis-dependent strand annealing or the canonical pathway that involves the formation of a double Holliday junction (Fig. 1). Single-strand annealing (SSA) is instead a Rad51-independent pathway that requires extensive resection of DNA between two repetitive sequences ( Fig. 1). DNA End Resection: When and What to ResectDSBs can form accidentally in any phase of the cell cycle upon exposure to ionizing radiation or chemicals or as a result of abortive processing of nucleic acids. Most DSBs, however, occur in S-phase when a DNA replication fork runs into a nick. Furthermore, DSBs are sometimes introduced "intentionally," such as in the prophase of the first meiotic division or during anticancer therapy regimens based on DNA-damaging agents (5). Depending on the cellular context, cells must first "decide" whether or not to resect the breaks (3, 4, 6, 7). DNA end resection commits the repair to HR and prevents NHEJ; therefore, it would be detrimental to resect DSBs in the G 1 phase of the cell cycle when no sister chromatid DNA is available as a template for repair. Cells have thus developed regulatory control mechanisms that activate resection only during the S or G 2 phases of the cell cycle, which will be introduced below (4, 6 -8).Another critical parameter is the pola...

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Section: Sgs1-dna2 Resection Pathwaymentioning

confidence: 99%

DNA End Resection: Nucleases Team Up with the Right Partners to Initiate Homologous Recombination

Ćejka

2015

Journal of Biological Chemistry

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186

199

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“…The Dna2 helicase exhibits only a weak 5 0 -3 0 unwinding activity on dsDNA and depends on the binding to free DNA ends before acting as a helicase (Bae et al 2002). However, recently, it was shown that Dna2 is a vigorous 5 0 -3 0 helicase in an S. cerevisiae nuclease dead mutant (Levikova et al 2013). Apparently, Dna2 depends on the binding to 5 0 -ssDNA flaps for processive helicase activity, and these flaps are degraded by the Dna2 nuclease domain of the wild-type protein (Levikova et al 2013).…”

Section: Structural Mechanisms Of Recombinationmentioning

confidence: 99%

“…However, recently, it was shown that Dna2 is a vigorous 5 0 -3 0 helicase in an S. cerevisiae nuclease dead mutant (Levikova et al 2013). Apparently, Dna2 depends on the binding to 5 0 -ssDNA flaps for processive helicase activity, and these flaps are degraded by the Dna2 nuclease domain of the wild-type protein (Levikova et al 2013). There may be a structural switch in Dna2 that regulates the balance between its nuclease and helicase activities.…”

Section: Structural Mechanisms Of Recombinationmentioning

confidence: 99%

Structural Studies of DNA End Detection and Resection in Homologous Recombination

Schiller

Seifert

Linke-Winnebeck

et al. 2014

Cold Spring Harbor Perspectives in Biology

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DNA double-strand breaks are repaired by two major pathways, homologous recombination or nonhomologous end joining. The commitment to one or the other pathway proceeds via different steps of resection of the DNA ends, which is controlled and executed by a set of DNA double-strand break sensors, endo-and exonucleases, helicases, and DNA damage response factors. The molecular choreography of the underlying protein machinery is beginning to emerge. In this review, we discuss the early steps of genetic recombination and double-strand break sensing with an emphasis on structural and molecular studies.

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“…Studies in Xenopus egg extracts as well as human cells show that another RecQ family of helicase Werner syndrome RecQ-like helicase (WRN) also promotes resection by unwinding the DNA ends and making it accessible for Dna2 [115][116][117][118][119]. Although Dna2 functions as both a helicase and a nuclease, only the nuclease activity is essential for the extension of DNA end resection [87,120,121]. The long stretch of ssDNA generated by Exo1 and Dna2 serves as the substrate for HR, and in the meantime prevents repair by NHEJ or MMEJ [9,92].…”

Section: Extension Of Resection By Exo1 and Dna2mentioning

confidence: 99%

Sharpening the ends for repair: mechanisms and regulation of DNA resection

Paudyal¹,

You²

2016

ABBS

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DNA end resection is a key process in the cellular response to DNA double-strand break damage that is essential for genome maintenance and cell survival. Resection involves selective processing of 5′ ends of broken DNA to generate ssDNA overhangs, which in turn control both DNA repair and checkpoint signaling. DNA resection is the first step in homologous recombination-mediated repair and a prerequisite for the activation of the ataxia telangiectasia mutated and Rad3-related (ATR)-dependent checkpoint that coordinates repair with cell cycle progression and other cellular processes. Resection occurs in a cell cycle-dependent manner and is regulated by multiple factors to ensure an optimal amount of ssDNA required for proper repair and genome stability. Here, we review the latest findings on the molecular mechanisms and regulation of the DNA end resection process and their implications for cancer formation and treatment.

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Nuclease activity of Saccharomyces cerevisiae Dna2 inhibits its potent DNA helicase activity

Cited by 55 publications

References 53 publications

DNA End Resection: Nucleases Team Up with the Right Partners to Initiate Homologous Recombination

DNA End Resection: Nucleases Team Up with the Right Partners to Initiate Homologous Recombination

Structural Studies of DNA End Detection and Resection in Homologous Recombination

Sharpening the ends for repair: mechanisms and regulation of DNA resection

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