title: Sae2 Function at DNA Double-Strand Breaks Is Bypassed by Dampening Tel1 or Rad53 Activity.
abstract: The MRX complex together with Sae2 initiates resection of DNA double-strand breaks (DSBs) to generate single-stranded DNA (ssDNA) that triggers homologous recombination. The absence of Sae2 not only impairs DSB resection, but also causes prolonged MRX binding at the DSBs that leads to persistent Tel1- and Rad53-dependent DNA damage checkpoint activation and cell cycle arrest. Whether this enhanced checkpoint signaling contributes to the DNA damage sensitivity and/or the resection defect of sae2Δ cells is not known. By performing a genetic screen, we identify rad53 and tel1 mutant alleles that suppress both the DNA damage hypersensitivity and the resection defect of sae2Δ cells through an Sgs1-Dna2-dependent mechanism. These suppression events do not involve escaping the checkpoint-mediated cell cycle arrest. Rather, defective Rad53 or Tel1 signaling bypasses Sae2 function at DSBs by decreasing the amount of Rad9 bound at DSBs. As a consequence, reduced Rad9 association to DNA ends relieves inhibition of Sgs1-Dna2 activity, which can then compensate for the lack of Sae2 in DSB resection and DNA damage resistance. We propose that persistent Tel1 and Rad53 checkpoint signaling in cells lacking Sae2 increases the association of Rad9 at DSBs, which in turn inhibits DSB resection by limiting the activity of the Sgs1-Dna2 resection machinery.
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Gobbini
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Villa
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Gnugnoli
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Menin
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Clerici
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy.
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Longhese
mesh_terms: D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics*; D064447:Checkpoint Kinase 2 / Q000235:genetics*; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage / Q000235:genetics; D004265:DNA Helicases / Q000235:genetics; D004720:Endonucleases / Q000235:genetics*; D042822:Genomic Instability / Q000235:genetics*; D059765:Homologous Recombination / Q000235:genetics; D006967:Hypersensitivity / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D053484:RecQ Helicases / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*
chemical_list: D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; C107849:SAE2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D064447:Checkpoint Kinase 2; D017346:Protein Serine-Threonine Kinases; C513623:TEL1 protein, S cerevisiae; C067022:RAD53 protein, S cerevisiae; D004720:Endonucleases; C090472:SGS1 protein, S cerevisiae; D004265:DNA Helicases; C410222:DNA2 protein, S cerevisiae; D053484:RecQ Helicases