Dual Control of Yen1 Nuclease Activity and Cellular Localization by Cdk and Cdc14 Prevents Genome Instability

The careful orchestration of cellular events such as DNA replication, repair, and segregation is essential for equal distribution of the duplicated genome into two daughter cells. To ensure that persistent recombination intermediates are resolved prior to cell division, the Yen1 Holliday junction resolvase is activated at anaphase. Here, we show that the master cell-cycle regulators, cyclin-dependent kinase (Cdk) and Cdc14 phosphatase, control the actions of Yen1. During S phase, Cdk-mediated phosphorylation of Yen1 promotes its nuclear exclusion and inhibits catalytic activity by reducing the efficiency of DNA binding. Later in the cell cycle, at anaphase, Cdc14 drives Yen1 dephosphorylation, leading to its nuclear relocalization and enzymatic activation. Using a constitutively activated form of Yen1, we show that uncontrolled Yen1 activity is detrimental to the cell: spatial and temporal restriction of Yen1 protects against genotoxic stress and, by avoiding competition with the noncrossover-promoting repair pathways, prevents loss of heterozygosity. [Display omitted] •Yen1 undergoes a dual mode of regulation: activity and subcellular localization•Cdk phosphorylation inhibits Yen1 at S phase by reducing its DNA binding affinity•Yen1 activation at anaphase is driven by the Cdc14 phosphatase•Premature activation of Yen1 leads to loss of heterozygosity and genome instability The complete elimination of DNA recombination intermediates is essential for chromosome segregation. Blanco et al. show that the master cell-cycle regulators Cdk and Cdc14 control both the localization and nuclease activation of the Holliday junction resolvase Yen1. Cdk/Cdc14 therefore control the final wave of joint molecule resolution at anaphase.