title: Ndd1 turnover by SCF(Grr1) is inhibited by the DNA damage checkpoint in Saccharomyces cerevisiae.
abstract: In Saccharomyces cerevisiae, Ndd1 is the dedicated transcriptional activator of the mitotic gene cluster, which includes thirty-three genes that encode key mitotic regulators, making Ndd1 a hub for the control of mitosis. Previous work has shown that multiple kinases, including cyclin-dependent kinase (Cdk1), phosphorylate Ndd1 to regulate its activity during the cell cycle. Previously, we showed that Ndd1 was inhibited by phosphorylation in response to DNA damage. Here, we show that Ndd1 is also subject to regulation by protein turnover during the mitotic cell cycle: Ndd1 is unstable during an unperturbed cell cycle, but is strongly stabilized in response to DNA damage. We find that Ndd1 turnover in metaphase requires Cdk1 activity and the ubiquitin ligase SCF(Grr1). In response to DNA damage, Ndd1 stabilization requires the checkpoint kinases Mec1/Tel1 and Swe1, the S. cerevisiae homolog of the Wee1 kinase. In both humans and yeast, the checkpoint promotes Wee1-dependent inhibitory phosphorylation of Cdk1 following exposure to DNA damage. While this is critical for checkpoint-induced arrest in most organisms, this is not true in budding yeast, where the function of damage-induced inhibitory phosphorylation is less well understood. We propose that the DNA damage checkpoint stabilizes Ndd1 by inhibiting Cdk1, which we show is required for targeting Ndd1 for destruction.
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America.
authors.forename: Ellen R
authors.initials: ER
authors.lastname: Edenberg
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Mark
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America.
authors.forename: David P
authors.initials: DP
authors.lastname: Toczyski
mesh_terms: D016203:CDC2 Protein Kinase / Q000096:biosynthesis / Q000235:genetics*; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000235:genetics*; D004249:DNA Damage / Q000235:genetics; D044783:F-Box Proteins / Q000096:biosynthesis / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008938:Mitosis / Q000235:genetics*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000235:genetics*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D044767:Ubiquitin-Protein Ligases / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D018797:Cell Cycle Proteins; D044783:F-Box Proteins; D047908:Intracellular Signaling Peptides and Proteins; C118820:NDD1 protein, S cerevisiae; C088385:RAD24 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C071032:GRR1 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; D016203:CDC2 Protein Kinase