title: Phosphorylation-regulated transitions in an oligomeric state control the activity of the Sae2 DNA repair enzyme.
abstract: In the DNA damage response, many repair and signaling molecules mobilize rapidly at the sites of DNA double-strand breaks. This network of immediate responses is regulated at the level of posttranslational modifications that control the activation of DNA processing enzymes, protein kinases, and scaffold proteins to coordinate DNA repair and checkpoint signaling. Here we investigated the DNA damage-induced oligomeric transitions of the Sae2 protein, an important enzyme in the initiation of DNA double-strand break repair. Sae2 is a target of multiple phosphorylation events, which we identified and characterized in vivo in the budding yeast Saccharomyces cerevisiae. Both cell cycle-dependent and DNA damage-dependent phosphorylation sites in Sae2 are important for the survival of DNA damage, and the cell cycle-regulated modifications are required to prime the damage-dependent events. We found that Sae2 exists in the form of inactive oligomers that are transiently released into smaller active units by this series of phosphorylations. DNA damage also triggers removal of Sae2 through autophagy and proteasomal degradation, ensuring that active Sae2 is present only transiently in cells. Overall, this analysis provides evidence for a novel type of protein regulation where the activity of an enzyme is controlled dynamically by posttranslational modifications that regulate its solubility and oligomeric state.
authors.affiliation: The Howard Hughes Medical Institute, Department of Molecular Biosciences, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Fu
authors.forename: Julia
authors.initials: J
authors.lastname: Chow
authors.forename: Kara A
authors.initials: KA
authors.lastname: Bernstein
authors.forename: Nodar
authors.initials: N
authors.lastname: Makharashvili
authors.forename: Sucheta
authors.initials: S
authors.lastname: Arora
authors.forename: Chia-Fang
authors.initials: CF
authors.lastname: Lee
authors.forename: Maria D
authors.initials: MD
authors.lastname: Person
authors.forename: Rodney
authors.initials: R
authors.lastname: Rothstein
authors.forename: Tanya T
authors.initials: TT
authors.lastname: Paull
mesh_terms: D001343:Autophagy / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000235:genetics*; D004720:Endonucleases / Q000235:genetics*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation / Q000235:genetics*; D046988:Proteasome Endopeptidase Complex / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D059748:Proteolysis; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C107849:SAE2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases; C513623:TEL1 protein, S cerevisiae; D004720:Endonucleases; D046988:Proteasome Endopeptidase Complex