Skip Navigation

Publication Detail

Title: A DNA nick at Ku-blocked double-strand break ends serves as an entry site for exonuclease 1 (Exo1) or Sgs1-Dna2 in long-range DNA end resection.

Authors: Wang, Weibin; Daley, James M; Kwon, Youngho; Xue, Xiaoyu; Krasner, Danielle S; Miller, Adam S; Nguyen, Kevin A; Williamson, Elizabeth A; Shim, Eun Yong; Lee, Sang Eun; Hromas, Robert; Sung, Patrick

Published In J Biol Chem, (2018 11 02)

Abstract: The repair of DNA double-strand breaks (DSBs) by homologous recombination (HR) is initiated by nucleolytic resection of the DNA break ends. The current model, being based primarily on genetic analyses in Saccharomyces cerevisiae and companion biochemical reconstitution studies, posits that end resection proceeds in two distinct stages. Specifically, the initiation of resection is mediated by the nuclease activity of the Mre11-Rad50-Xrs2 (MRX) complex in conjunction with its cofactor Sae2, and long-range resection is carried out by exonuclease 1 (Exo1) or the Sgs1-Top3-Rmi1-Dna2 ensemble. Using fully reconstituted systems, we show here that DNA with ends occluded by the DNA end-joining factor Ku70-Ku80 becomes a suitable substrate for long-range 5'-3' resection when a nick is introduced at a locale proximal to one of the Ku-bound DNA ends. We also show that Sgs1 can unwind duplex DNA harboring a nick, in a manner dependent on a species-specific interaction with the ssDNA-binding factor replication protein A (RPA). These biochemical systems and results will be valuable for guiding future endeavors directed at delineating the mechanistic intricacy of DNA end resection in eukaryotes.

PubMed ID: 30224356 Exiting the NIEHS site

MeSH Terms: DNA Breaks, Double-Stranded*; DNA Helicases/genetics; DNA Helicases/metabolism*; DNA Repair; DNA-Binding Proteins/genetics; DNA-Binding Proteins/metabolism*; Exodeoxyribonucleases/genetics; Exodeoxyribonucleases/metabolism*; Homologous Recombination; RecQ Helicases/genetics; RecQ Helicases/metabolism*; Replication Protein A/genetics; Replication Protein A/metabolism*; Saccharomyces cerevisiae Proteins/genetics; Saccharomyces cerevisiae Proteins/metabolism*; Saccharomyces cerevisiae/enzymology; Saccharomyces cerevisiae/genetics*; Saccharomyces cerevisiae/metabolism

Back
to Top