Validation and application of Drosophila melanogaster as an in vivo model for the detection of double strand breaks by neutral Comet assay

Abstract A model system for studying double-strand-break (DSB)-induced genetic recombination in vivo based on the ets1 segCΔ strain of bacteriophage T4 was developed. The ets1, a 66-bp DNA fragment of phage T2L containing the cleavage site for the T4 SegC site-specific endonuclease, was inserted into the proximal part of the T4 rIIB gene. Under segC+ conditions, the ets1 behaves as a recombination hotspot. Crosses of the ets1 against rII markers located to the left and to the right of ets1 gave similar results, thus demonstrating the equal and symmetrical initiation of recombination by either part of the broken chromosome. Frequency/distance relationships were studied in a series of two- and three-factor crosses with other rIIB and rIIA mutants (all segC+) separated from ets1 by 12-2100 bp. The observed relationships were readily interpretable in terms of the modified splice/patch coupling model. The advantages of this localized or focused recombination over that distributed along the chromosome, as a model for studying the recombination-replication pathway in T4 in vivo, are discussed.

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Involvement of Ku80 in microhomology-mediated end joining for DNA double-strand breaks in vivo

DNA Repair ◽

10.1016/j.dnarep.2006.12.002 ◽

2007 ◽

Vol 6 (5) ◽

pp. 639-648 ◽

Cited By ~ 19

Author(s):

Yukitaka Katsura ◽

Shigeru Sasaki ◽

Masanori Sato ◽

Kiyoshi Yamaoka ◽

Kazumi Suzukawa ◽

...

Keyword(s):

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

End Joining ◽

Strand Breaks

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Autophosphorylation of DNA-PKCS regulates its dynamics at DNA double-strand breaks

The Journal of Cell Biology ◽

10.1083/jcb.200608077 ◽

2007 ◽

Vol 177 (2) ◽

pp. 219-229 ◽

Cited By ~ 256

Author(s):

Naoya Uematsu ◽

Eric Weterings ◽

Ken-ichi Yano ◽

Keiko Morotomi-Yano ◽

Burkhard Jakob ◽

...

Keyword(s):

Kinase Activity ◽

Laser System ◽

Double Strand Breaks ◽

Dependent Manner ◽

Dna Double Strand Breaks ◽

End Joining ◽

Dsb Repair ◽

Strand Breaks ◽

Dna Ends

The DNA-dependent protein kinase catalytic subunit (DNA-PKCS) plays an important role during the repair of DNA double-strand breaks (DSBs). It is recruited to DNA ends in the early stages of the nonhomologous end-joining (NHEJ) process, which mediates DSB repair. To study DNA-PKCS recruitment in vivo, we used a laser system to introduce DSBs in a specified region of the cell nucleus. We show that DNA-PKCS accumulates at DSB sites in a Ku80-dependent manner, and that neither the kinase activity nor the phosphorylation status of DNA-PKCS influences its initial accumulation. However, impairment of both of these functions results in deficient DSB repair and the maintained presence of DNA-PKCS at unrepaired DSBs. The use of photobleaching techniques allowed us to determine that the kinase activity and phosphorylation status of DNA-PKCS influence the stability of its binding to DNA ends. We suggest a model in which DNA-PKCS phosphorylation/autophosphorylation facilitates NHEJ by destabilizing the interaction of DNA-PKCS with the DNA ends.

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A DNA-binding protein from Ustilago maydis prefers duplex DNA without chain interruptions.

Molecular and Cellular Biology ◽

10.1128/mcb.3.4.605 ◽

1983 ◽

Vol 3 (4) ◽

pp. 605-612 ◽

Cited By ~ 2

Author(s):

J R Rusche ◽

W K Holloman

Keyword(s):

Drosophila Melanogaster ◽

Satellite Dna ◽

Binding Assay ◽

Ustilago Maydis ◽

Dna Binding Protein ◽

Double Strand Breaks ◽

Duplex Dna ◽

Plasmid Pbr322 ◽

Strand Breaks ◽

Dna Strand

Using a nitrocellulose filter binding assay, we have partially purified a protein from mitotic cells of Ustilago maydis that binds preferentially to covalently closed circular duplex DNA. DNA containing single- or double-strand breaks is bound poorly by the protein. Once formed, the DNA-protein complex is stable, resisting dissociation in high salt. However, when a DNA strand is broken, the complex appears to dissociate. The protein binds equally well to form I DNA of phi X174 or the plasmid pBR322, but has a higher affinity for a hybrid plasmid containing a cloned region of Drosophila melanogaster satellite DNA.

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Genetic Separation of Sae2 Nuclease Activity from Mre11 Nuclease Functions in Budding Yeast

Molecular and Cellular Biology ◽

10.1128/mcb.00156-17 ◽

2017 ◽

Vol 37 (24) ◽

Cited By ~ 8

Author(s):

Sucheta Arora ◽

Rajashree A. Deshpande ◽

Martin Budd ◽

Judy Campbell ◽

America Revere ◽

...

Keyword(s):

Nuclease Activity ◽

Double Strand Breaks ◽

Endonuclease Activity ◽

Dna Double Strand Breaks ◽

Dna Breaks ◽

Content Type ◽

Strand Breaks ◽

Dna Ends

ABSTRACT Sae2 promotes the repair of DNA double-strand breaks in Saccharomyces cerevisiae. The role of Sae2 is linked to the Mre11/Rad50/Xrs2 (MRX) complex, which is important for the processing of DNA ends into single-stranded substrates for homologous recombination. Sae2 has intrinsic endonuclease activity, but the role of this activity has not been assessed independently from its functions in promoting Mre11 nuclease activity. Here we identify and characterize separation-of-function mutants that lack intrinsic nuclease activity or the ability to promote Mre11 endonucleolytic activity. We find that the ability of Sae2 to promote MRX nuclease functions is important for DNA damage survival, particularly in the absence of Dna2 nuclease activity. In contrast, Sae2 nuclease activity is essential for DNA repair when the Mre11 nuclease is compromised. Resection of DNA breaks is impaired when either Sae2 activity is blocked, suggesting roles for both Mre11 and Sae2 nuclease activities in promoting the processing of DNA ends in vivo. Finally, both activities of Sae2 are important for sporulation, indicating that the processing of meiotic breaks requires both Mre11 and Sae2 nuclease activities.

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