Genetic separation of Sae2 nuclease activity from Mre11 nuclease functions in budding yeast
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 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.
© 2017 American Society for Microbiology. Accepted manuscript posted online 2 October 2017. We are grateful for yeast strains and plasmids from James Haber, Lorraine Symington, Kirill Lobachev, John Petrini, Sang Eun Lee, Katsunori Sugimoto, and Xiaolan Zhao. Work in the Paull lab was supported in part by the Cancer Prevention and Research Institute of Texas, RP110465 and R01GM081425 to K.H.S. from the National Institutes of Health.
Published - Mol._Cell._Biol.-2017-Arora-.pdf