Separase cooperates with Zds1 and Zds2 to activate Cdc14 phosphatase in early anaphase

Abstract

Completion of mitotic exit and cytokinesis requires the inactivation of mitotic cyclin-dependent kinase (Cdk) activity. A key enzyme that counteracts Cdk during budding yeast mitotic exit is the Cdc14 phosphatase. Cdc14 is inactive for much of the cell cycle, sequestered by its inhibitor Net1 in the nucleolus. At anaphase onset, separase-dependent down-regulation of PP2ACdc55 allows phosphorylation of Net1 and consequent Cdc14 release. How separase causes PP2ACdc55 down-regulation is not known. Here, we show that two Cdc55-interacting proteins, Zds1 and Zds2, contribute to timely Cdc14 activation during mitotic exit. Zds1 and Zds2 are required downstream of separase to facilitate nucleolar Cdc14 release. Ectopic Zds1 expression in turn is sufficient to down-regulate PP2ACdc55 and promote Net1 phosphorylation. These findings identify Zds1 and Zds2 as new components of the mitotic exit machinery, involved in activation of the Cdc14 phosphatase at anaphase onset. Our results suggest that these proteins may act as separase-regulated PP2ACdc55 inhibitors.

Comparative genetic analysis of PP2A-Cdc55 regulators in budding yeast

“…4 In budding yeast, cells lacking Cdc55 (a regulatory B subunit) exhibit multiple cell cycle defects, including mitotic entry, [5][6][7][8][9][10] spindle assembly checkpoint (SAC), 5,[11][12][13] and precocious mitotic exit. 12,[14][15][16][17][18] We have proposed previously that PP2A-Cdc55 activity is largely controlled by its subcellular distribution. 13,16 Cdc55 binding protein Zds1 (zillion different screens) and its homolog Zds2 are cytoplasmic proteins and sequester Cdc55 from the nucleus during mitosis.…”

“…[19][20][21] Second, zds1Δ zds2Δ cells are also impaired in mitotic exit, because nuclear PP2A-Cdc55 activity prevents activation of a Cdc14 phosphatase. 14,15 These phenotypes of zds1Δ zds2Δ cells are due to nuclear accumulation of Cdc55, because either deletion or nuclear exclusion of Cdc55 rescues both phenotypes.…”

How to halve ploidy: lessons from budding yeast meiosis

“…Inhibition of PP2A Cdc55 by separase (which triggers the metaphaseanaphase transition by destroying sister chromatid cohesion) results in Net1 phosphorylation and Cdc14 release from the nucleolus ( Figure 4C). The precise mechanism how separase inhibits PP2A Cdc55 is not known but it requires assistance from two fungal-specific proteins Zds1 and Zds2 [86] and the kinetochore protein Slk19. Interestingly the proteolytic activity of separase is not required for its FEAR function.…”

Clan CD of cysteine peptidases as an example of evolutionary divergences in related protein families across plant clades

“…Separases are mainly involved in the reléase of chromosome cohesión at the metaphaseanaphase transition and the subsequent separation of sister chromatids by cleaving of the cohesin kleisin (SCC1) subunit during eukaryotic mitosis and meiosis (Queralt and Uhlmann, 2005;Liu and Makaroff, 2006). Separases have been implicated in some other processes as in anaphase spindle stabilization or in cell cycle progression (Papi et al, 2005;Queralt andUhlmann, 2005, 2008). As cell cycle is a general process, separases are expected to be present in all plant species.…”