Cdc6 is sequentially regulated by PP2A-Cdc55, Cdc14, and Sic1 for origin licensing in S. cerevisiae

eLife

Dirk Remus¹  John FX Diffley²  Shaneen Singh³  Amy E Ikui³  Andriele Silva³  Jasmin Philip³  Mihkel Örd⁴  Mart Loog⁴ 

[1] Memorial Sloan-Kettering Cancer Center, New York, United States;The Francis Crick Institute, London, United Kingdom;The PhD Program in Biochemistry, The Graduate Center, CUNY, Brooklyn, United States;Brooklyn College, Brooklyn, United States;University of Tartu, Tartu, Estonia;

关键词: Cdc6;    PP2A;    Cdc55;    DNA replication;    phosphatase;    Cdc14;    S. cerevisiae;   

DOI  :  10.7554/eLife.74437

来源: eLife Sciences Publications, Ltd

【 摘 要 】

Cdc6, a subunit of the pre-replicative complex (pre-RC), contains multiple regulatory cyclin-dependent kinase (Cdk1) consensus sites, SP or TP motifs. In Saccharomyces cerevisiae, Cdk1 phosphorylates Cdc6-T7 to recruit Cks1, the Cdk1 phospho-adaptor in S phase, for subsequent multisite phosphorylation and protein degradation. Cdc6 accumulates in mitosis and is tightly bound by Clb2 through N-terminal phosphorylation in order to prevent premature origin licensing and degradation. It has been extensively studied how Cdc6 phosphorylation is regulated by the cyclin–Cdk1 complex. However, a detailed mechanism on how Cdc6 phosphorylation is reversed by phosphatases has not been elucidated. Here, we show that PP2ACdc55 dephosphorylates Cdc6 N-terminal sites to release Clb2. Cdc14 dephosphorylates the C-terminal phospho-degron, leading to Cdc6 stabilization in mitosis. In addition, Cdk1 inhibitor Sic1 releases Clb2·Cdk1·Cks1 from Cdc6 to load Mcm2–7 on the chromatin upon mitotic exit. Thus, pre-RC assembly and origin licensing are promoted by phosphatases through the attenuation of distinct Cdk1-dependent Cdc6 inhibitory mechanisms.

【 授权许可】

CC BY