Università della Svizzera italiana

Main steps in DNA double-strand break repair : An introduction to homologous recombination and related processes

Ranjha, Lepakshi ; Howard, Sean Michael ; Cejka, Petr

In: Chromosoma, 2018, vol. 127, no. 2 (June), p. 187–214

DNA double-strand breaks arise accidentally upon exposure of DNA to radiation, chemicals or result from faulty DNA metabolic processes. DNA breaks can also be introduced in a programmed manner, such as during the maturation of the immune system, meiosis or cancer chemo- or radiotherapy. Cells have developed a variety of repair pathways, which are fine-tuned to the specific needs of a cell....

Public access from Aug 20, 2019
Università della Svizzera italiana

NBS1 promotes the endonuclease of the MRE11-RAD50 complex by sensing CtIP phosphorylation

Anand, Roopesh ; Jasrotia, Arti ; Bundschuh, Diana ; Howard, Sean Michael ; Ranjha, Lepakshi ; Stucki, Manuel ; Cejka, Petr

In: The EMBO Journal, 2019, vol. 38, no. 7, p. e101005

DNA end resection initiates DNA break repair by homologous recombination. MRE11-RAD50-NBS1 and phosphorylated CtIP perform the first resection step by MRE11-catalyzed endonucleolytic DNA cleavage. Human NBS1, more than its Xrs2 homologue from Saccharomyces cerevisiae, is crucial for this process, highlighting complex mechanisms that regulate the MRE11 nuclease in high eukaryotes. Using a...

Public access from Jul 28, 2019
Università della Svizzera italiana

Stepwise 5' DNA end-specific resection of DNA breaks by the Mre11-Rad50-Xrs2 and Sae2 nuclease ensemble

Cannavo, Elda ; Reginato, Giordano ; Cejka, Petr

In: Proceedings of the national academy of sciences of the United States of America, 2019, vol. 116, no. 12 (March 19), p. 5505-5513

To repair DNA double-strand breaks by homologous recombination, the 5′-terminated DNA strands must first be resected to produce 3′ overhangs. Mre11 from Saccharomyces cerevisiae is a 3′ → 5′ exonuclease that is responsible for 5′ end degradation in vivo. Using plasmid-length DNA substrates and purified recombinant proteins, we show that the combined exonuclease and endonuclease...

Università della Svizzera italiana

The motor activity of DNA2 functions as an ssDNA translocase to promote DNA end resection

Levikova, Maryna ; Pinto, Cosimo ; Cejka, Petr

In: Genes and Development, 2017, vol. 31, no. 5, p. 493-502

DNA2 nuclease–helicase functions in DNA replication and recombination. This requires the nuclease of DNA2, while, in contrast, the role of the helicase activity has been unclear. We now show that the motor activity of both recombinant yeast and human DNA2 promotes efficient degradation of long stretches of ssDNA, particularly in the presence of the replication protein A. This degradation is...

Università della Svizzera italiana

Physiological protein blocks direct the Mre11–Rad50–Xrs2 and Sae2 nuclease complex to initiate DNA end resection

Reginato, Giordano ; Cannavo, Elda ; Cejka, Petr

In: Genes and Development, 2017, vol. 31, no. 23-24, p. 2325-2330

DNA double-strand break repair by homologous recombination is initiated by DNA end resection, which is commenced by the Mre11–Rad50–Xrs2 complex and Sae2 in yeast. Here we report that the nonhomologous end joining factor Ku limits the exonuclease activity of Mre11 and promotes its endonuclease to cleave 5'-terminated DNA strands at break sites. Following initial endonucleolytic cleavage...