title: Two distinct pathways for inhibiting pds1 ubiquitination in response to DNA damage.
abstract: The presence of DNA damage activates a conserved cellular response known as the DNA damage checkpoint pathway. This pathway induces a cell cycle arrest that persists until the damage is repaired. Consequently, the failure to arrest in response to DNA damage is associated with genomic instability. In budding yeast, activation of the DNA damage checkpoint pathway leads to a mitotic cell cycle arrest. Following the detection of DNA damage, the checkpoint signal is transduced via the Mec1 kinase, which in turn activates two kinases, Rad53 and Chk1 that act in parallel pathways to bring about the cell cycle arrest. The downstream target of Rad53 is unknown. The target of Chk1 is Pds1, an inhibitor of anaphase initiation whose degradation is a prerequisite for mitotic progression. Pds1 degradation is dependent on its ubiquitination by the anaphase-promoting complex/cyclosome ubiquitin ligase, acting in conjunction with the Cdc20 protein (APC/CCdc20). Previous studies showed that the Rad53 and Chk1 pathways independently lead to Pds1 stabilization but the mechanism for this was unknown. In the present study we show that both the Chk1 and the Rad53 pathways inhibit the APC/CCdc20-dependent ubiquitination of Pds1 but they affect different steps of the process: the Rad53 pathway inhibits the Pds1-Cdc20 interaction whereas Chk1-dependent phosphorylation of Pds1 inhibits the ubiquitination reaction itself. Finally, we show that once the DNA damage is repaired, Pds1 dephosphorylation is involved in the recovery from the checkpoint induced cell cycle arrest.
authors.affiliation: Laboratory of Molecular and Cellular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Ritu
authors.initials: R
authors.lastname: Agarwal
authors.forename: Zhanyun
authors.initials: Z
authors.lastname: Tang
authors.forename: Hongtao
authors.initials: H
authors.lastname: Yu
authors.forename: Orna
authors.initials: O
authors.lastname: Cohen-Fix
mesh_terms: D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D004260:DNA Repair; D004271:DNA, Fungal / Q000378:metabolism / Q000528:radiation effects; D005656:Fungal Proteins; D005720:Gamma Rays; D047908:Intracellular Signaling Peptides and Proteins; D008938:Mitosis; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011994:Recombinant Proteins; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D064249:Securin; D015398:Signal Transduction; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: C577495:CDC20 protein, S cerevisiae; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; C578004:PDS1 protein, S cerevisiae; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D064249:Securin; D025801:Ubiquitin; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; D000071877:Checkpoint Kinase 1; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C067022:RAD53 protein, S cerevisiae