Wolfe Benjamin A, Gould Kathleen L
Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA.
EMBO J. 2004 Feb 25;23(4):919-29. doi: 10.1038/sj.emboj.7600103. Epub 2004 Feb 12.
The Cdc14 family of phosphatases specifically reverses proline-directed phosphorylation events. In Saccharomyces cerevisiae, Cdc14p promotes Cdk1p inactivation at mitotic exit by reversing Cdk1p-dependent phosphorylations. Cdk1p is a proline-directed kinase whose activity is required in all eukaryotes for the transit into mitosis. At mitotic commitment, Cdk1p participates in its own regulation by activating the mitotic inducing phosphatase, Cdc25p, and inhibiting the opposing kinase, Wee1p. We have investigated the ability of Schizosaccharomyces pombe Clp1p, a Cdc14p homolog, to disrupt this auto-amplification loop. We show here that Clp1p is required to dephosphorylate, destabilize, and inactivate Cdc25p at the end of mitosis. Clp1p promotes recognition of Cdc25p by the anaphase-promoting complex/cyclosome, an E3 ubiquitin ligase. Failure to inactivate and destabilize Cdc25p in late mitosis delays progression through anaphase, interferes with septation initiation network signaling, and additionally advances the commitment to mitotic entry in the next cycle. This may be a widely conserved mechanism whereby Cdc14 proteins contribute to Cdk1p inactivation.
磷酸酶Cdc14家族特异性地逆转脯氨酸定向的磷酸化事件。在酿酒酵母中,Cdc14p通过逆转依赖Cdk1p的磷酸化作用,在有丝分裂末期促进Cdk1p失活。Cdk1p是一种脯氨酸定向激酶,其活性在所有真核生物进入有丝分裂过程中都是必需的。在有丝分裂承诺期,Cdk1p通过激活有丝分裂诱导磷酸酶Cdc25p和抑制拮抗激酶Wee1p来参与自身的调节。我们研究了粟酒裂殖酵母Clp1p(一种Cdc14p同源物)破坏这种自放大环的能力。我们在此表明,Clp1p在有丝分裂末期是使Cdc25p去磷酸化、使其不稳定并使其失活所必需的。Clp1p促进后期促进复合物/细胞周期体(一种E3泛素连接酶)对Cdc25p的识别。在有丝分裂后期未能使Cdc25p失活并使其不稳定会延迟后期进程,干扰隔膜起始网络信号传导,并额外提前下一个周期进入有丝分裂的承诺。这可能是一种广泛保守的机制,通过该机制Cdc14蛋白有助于Cdk1p失活。