biostudies-literatureUnknown32(24)Manfrini NThe Mec1 and Rad53 protein kinases are essential for budding yeast cell viability and are also required to activate the S-phase checkpoint, which supports DNA replication under stress conditions. Whether these two functions are related to each other remains to be determined, and the nature of the replication stress-dependent lethality of mec1 and rad53 mutants is still unclear. We show here that a decrease in cyclin-dependent kinase 1 (Cdk1) activity alleviates the lethal effects of mec1 and rad53 mutations both in the absence and in the presence of replication stress, indicating that the execution of a certain Cdk1-mediated event(s) is detrimental in the absence of Mec1 and Rad53. This lethality involves Cdk1 functions in both G(1) and mitosis. In fact, delaying either the G(1)/S transitiMolecular and cellular biology4971-85https://www.ebi.ac.uk/biostudies/studies/S-EPMC3510536biostudies-literatureG(1)/S and G(2)/M cyclin-dependent kinase activities commit cells to death in the absence of the S-phase checkpoint.PMC3510536Trovesi CGobbini ELucchini GManfrini NLonghese MPBaldo VfalseG(1)/S and G(2)/M cyclin-dependent kinase activities commit cells to death in the absence of the S-phase checkpoint.The Mec1 and Rad53 protein kinases are essential for budding yeast cell viability and are also required to activate the S-phase checkpoint, which supports DNA replication under stress conditions. Whether these two functions are related to each other remains to be determined, and the nature of the replication stress-dependent lethality of mec1 and rad53 mutants is still unclear. We show here that a decrease in cyclin-dependent kinase 1 (Cdk1) activity alleviates the lethal effects of mec1 and rad53 mutations both in the absence and in the presence of replication stress, indicating that the execution of a certain Cdk1-mediated event(s) is detrimental in the absence of Mec1 and Rad53. This lethality involves Cdk1 functions in both G(1) and mitosis. In fact, delaying either the G(1)/S transiti2012-01-01T00:00:00Z2012 Dec2025-05-29T22:28:38.075Z2025-05-29T22:28:38.075ZS-EPMC35105362304538810.1128/mcb.00956-1210.1128/MCB.00956-12