Identification of the Xenopus DNA2 protein as a major nuclease for the 5'-&gt;3' strand-specific processing of DNA ends

Liao, Shuren; Toczylowski, Thomas; Yan, Hong

doi:10.1093/nar/gkn616

Cited by 67 publications

(81 citation statements)

References 38 publications

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“…In agreement with these findings, it has been observed that cells depleted of both BLM and EXO1 show a reduction in the formation of RPA foci in response to DSBs and are defective in DSB repair by HR (16,19). However, studies using Xenopus egg extracts and purified proteins have shown that Dna2 mediates DNA end resection together with WRN rather than BLM (21)(22)(23). This discrepancy prompted us to investigate the role of WRN in DNA end resection in human cells.…”

mentioning

confidence: 69%

DNA2 Cooperates with the WRN and BLM RecQ Helicases to Mediate Long-range DNA End Resection in Human Cells

Sturzenegger

Burdová

Kanagaraj

et al. 2014

Journal of Biological Chemistry

184

163

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Background: DNA end resection is a critical step in the homology-directed repair of DNA double strand breaks (DSBs). Results: Human WRN helicase stimulates the DNA2-catalyzed resection of DNA ends and acts in concert with DNA2 to promote DSB repair by single strand annealing. Conclusion: DNA2 cooperates with WRN or BLM to mediate the resection of DSBs in mammalian cells. Significance: Defects in DNA end resection might, in part, account for the genomic instability phenotype of Werner syndrome.

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mentioning

confidence: 69%

DNA2 Cooperates with the WRN and BLM RecQ Helicases to Mediate Long-range DNA End Resection in Human Cells

Sturzenegger

Burdová

Kanagaraj

et al. 2014

Journal of Biological Chemistry

184

163

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“…However, in contrast to FEN1, Dna2 is an essential gene in yeast, suggesting that other proteins, including FEN1, cannot compensate for its loss in DNA replication or that it possesses functions beyond its role in Okazaki fragment processing. In agreement with this, genetic and biochemical studies have implicated Dna2 in DNA double-strand break (DSB) repair, telomere regulation, and mitochondrial function (8,10,15,26,38,44,45).Analysis of Dna2 in yeast revealed that it undergoes dynamic cell cycle localization. Dna2 localizes to telomeres during G 1 , relocalizes throughout the genome in S phase, and moves back to the telomere during late S/G 2 , where it participates in telomere replication and telomerase-dependent telomere elongation (10).…”

mentioning

confidence: 71%

“…These phenotypes may be explained by recent work demonstrating that Dna2 plays an important role in 5Ј-end resection following DSBs. Indeed, upon induction of DSBs and initiation of 5Ј-end resection by the Mre11-Rad50-Xrs2 complex, Dna2 and Sgs1 cooperate to further degrade the 5Ј end, creating long 3Ј strands essential for homologous recombination (26,45). Finally, while dna2⌬ mutations are lethal in budding yeast, the dna2⌬ pif1-m2 (nuclear PIF1) double mutations rescue dna2⌬ lethality but produce a petite phenotype, suggesting that Dna2 is also involved in mtDNA maintenance (8).…”

mentioning

confidence: 99%

Human Dna2 Is a Nuclear and Mitochondrial DNA Maintenance Protein

Duxin¹,

Dao²,

Martinsson

et al. 2009

Molecular and Cellular Biology

172

192

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Dna2 is a highly conserved helicase/nuclease that in yeast participates in Okazaki fragment processing, DNA repair, and telomere maintenance. Here, we investigated the biological function of human Dna2 (hDna2).Immunofluorescence and biochemical fractionation studies demonstrated that hDna2 was present in both the nucleus and the mitochondria. Analysis of mitochondrial hDna2 revealed that it colocalized with a subfraction of DNA-containing mitochondrial nucleoids in unperturbed cells. Upon the expression of disease-associated mutant forms of the mitochondrial Twinkle helicase which induce DNA replication pausing/stalling, hDna2 accumulated within nucleoids. RNA interference-mediated depletion of hDna2 led to a modest decrease in mitochondrial DNA replication intermediates and inefficient repair of damaged mitochondrial DNA. Importantly, hDna2 depletion also resulted in the appearance of aneuploid cells and the formation of internuclear chromatin bridges, indicating that nuclear hDna2 plays a role in genomic DNA stability. Together, our data indicate that hDna2 is similar to its yeast counterpart and is a new addition to the growing list of proteins that participate in both nuclear and mitochondrial DNA maintenance.DNA damage arises from errors in the replication process, as well as a myriad of intrinsic and extrinsic DNA-damaging agents that continually assault cells. Failure to efficiently repair DNA lesions leads to accumulation of mutations that contribute to numerous pathologies, including carcinogenesis. In addition to genomic DNA, mitochondrial DNA (mtDNA) is subject to damage that requires repair to maintain integrity. For these reasons, it is not surprising that DNA replication and repair proteins display significant plasticity that allows participation in several divergent replication and repair processes. In addition, numerous mechanisms, including alternative splicing, posttranslational modifications, or utilization of alternative translation initiation start sites, allow DNA replication and repair proteins such as Pif1, DNA ligase III, and APE1 to localize to the nucleus and the mitochondrion and participate in DNA replication and/or repair (9, 17, 25), thus ensuring genomic DNA and mtDNA integrity.Dna2 is an evolutionarily conserved helicase/nuclease enzyme. Originally discovered in Saccharomyces cerevisiae, Dna2 orthologs are found throughout the animal kingdom, including humans (5,22,28). Early studies demonstrated that Dna2 functions in concert with Flap endonuclease 1 (FEN1) to remove long DNA flaps that form upon lagging-strand DNA replication (6). However, in contrast to FEN1, Dna2 is an essential gene in yeast, suggesting that other proteins, including FEN1, cannot compensate for its loss in DNA replication or that it possesses functions beyond its role in Okazaki fragment processing. In agreement with this, genetic and biochemical studies have implicated Dna2 in DNA double-strand break (DSB) repair, telomere regulation, and mitochondrial function (8,10,15,26,38,44,45).Analysis of Dna2 in yeas...

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“…Helicase activities of Xenopus laevis and human Dna2 were considered to be either non-existent or extremely weak (22,35). The robust nuclease activity of Dna2 tends to obscure detection of its unwinding property.…”

Section: Discussionmentioning

confidence: 99%

“…Whereas the helicase activity of yeast Dna2 is dispensable under certain growth conditions, its endonuclease activity is essential. How-ever, growth defects in the helicase mutants demonstrate that the helicase is important for Dna2 physiological function in vivo (17 The endonuclease activity of Dna2 has been shown to play a role in Okazaki maturation (20), telomere maintenance (21), double strand break repair (22)(23)(24)(25), long patch base excision repair (26), and aging (27). However, with the exception of showing unwinding of G4 quartets by Dna2 helicase (28) and showing that mutation of the helicase relatively few studies have been focused on understanding its roles.…”

mentioning

confidence: 99%

Dna2 Exhibits a Unique Strand End-dependent Helicase Function

Balakrishnan

Polaczek

Pokharel

et al. 2010

Journal of Biological Chemistry

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Dna2 endonuclease/helicase participates in eukaryotic DNA transactions including cleavage of long flaps generated during Okazaki fragment processing. Its unusual substrate interaction consists of recognition and binding of the flap base, then threading over the 5-end of the flap, and cleaving periodically to produce a terminal product ϳ5 nt in length. Blocking the 5-end prevents cleavage. The Dna2 ATP-driven 5 to 3 DNA helicase function promotes motion of Dna2 on the flap, presumably aiding its nuclease function. Here we demonstrate using two different nuclease-dead Dna2 mutants that on substrates simulating Okazaki fragments, Dna2 must thread onto an unblocked 5 flap to display helicase activity. This requirement is maintained on substrates with single-stranded regions thousands of nucleotides in length. To our knowledge this is the first description of a eukaryotic helicase that cannot load onto its tracking strand internally but instead must enter from the end. Biologically, the loading requirement likely helps the helicase to coordinate with the Dna2 nuclease function to prevent creation of undesirably long flaps during DNA transactions.DNA and RNA perform their biological roles in either double-stranded, double helical or single-stranded configurations. Functions requiring access to the nucleotide bases involve conversion of double to single strands, a process that requires energy and is carried out by the helicases. These motor proteins derive their energy from nucleoside triphosphate, usually adenosine triphosphate (ATP), hydrolysis (1). Helicases have evolved to bind and act in a sequence-independent manner on DNA, RNA, or DNA-RNA hybrid duplexes. Each helicase exhibits a specific directionality of unwinding, defined by the tracking orientation, either 5Ј to 3Ј or 3Ј to 5Ј on one strand of the substrate. The basic mechanism involves binding to the strand on which tracking occurs and then translocation that pushes away the complementary strand.

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Identification of the Xenopus DNA2 protein as a major nuclease for the 5'->3' strand-specific processing of DNA ends

Cited by 67 publications

References 38 publications

DNA2 Cooperates with the WRN and BLM RecQ Helicases to Mediate Long-range DNA End Resection in Human Cells

DNA2 Cooperates with the WRN and BLM RecQ Helicases to Mediate Long-range DNA End Resection in Human Cells

Human Dna2 Is a Nuclear and Mitochondrial DNA Maintenance Protein

Dna2 Exhibits a Unique Strand End-dependent Helicase Function

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