Genetic and biochemical evaluation of the importance of Cdc6 in regulating mitotic exit
Genetic and biochemical evaluation of the importance of Cdc6 in regulating mitotic exit
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DOI：
10.1091/mbc.e03-06-0384
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发表时间：
2003-11-01
影响因子：
3.3
通讯作者：
Cross, FR
中科院分区：
文献类型：
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作者：
Archambault, V;Li, CHX;Cross, FR
我们评估了复制控制蛋白Cdc 6的N-末端区域作为细胞周期蛋白依赖性激酶（Cdk）活性的抑制剂，促进有丝分裂退出的假设。Cdc 6的积累被限制在从中期细胞周期，直到随后的G1期，由于蛋白水解的控制，需要Cdc 6的N-末端区域。在有丝分裂晚期，Cdc 6的水平与Sic 1相当，并与有丝分裂细胞周期蛋白Clb 2特异性结合。Cdc 6的适度过表达促进CLB 2Deltadb菌株的活力，否则在有丝分裂退出时停滞，并且拯救依赖于N-末端推定的Cdk抑制结构域。这些观察结果支持Cdc 6抑制Clb 2-Cdk的潜力，从而促进有丝分裂退出。与这一想法一致，我们观察到的胞质分裂缺陷cdh 1 Δ sic 1 Δ cdc 6 Δ 2 -49三重突变体。然而，我们能够构建可行的菌株，在三个不同的背景下，既不包含SIC 1也不包含Cdc 6 Cdk抑制结构域，与以前的工作相矛盾。因此，我们得出结论，虽然Cdc 6和Sic 1有可能通过抑制Clb 2-Cdk促进有丝分裂退出，但有丝分裂退出不需要任何确定的化学计量的Cdk活性抑制剂。
We evaluated the hypothesis that the N-terminal region of the replication control protein Cdc6 acts as an inhibitor of cyclin-dependent kinase (Cdk) activity, promoting mitotic exit. Cdc6 accumulation is restricted to the period from mid-cell cycle until the succeeding G1, due to proteolytic control that requires the Cdc6 N-terminal region. During late mitosis, Cdc6 is present at levels comparable with Sic1 and binds specifically to the mitotic cyclin Clb2. Moderate overexpression of Cdc6 promotes viability of CLB2Deltadb strains, which otherwise arrest at mitotic exit, and rescue is dependent on the N-terminal putative Cdk-inhibitory domain. These observations support the potential for Cdc6 to inhibit Clb2-Cdk, thus promoting mitotic exit. Consistent with this idea, we observed a cytokinesis defect in cdh1Delta sic1Delta cdc6Delta2-49 triple mutants. However, we were able to construct viable strains, in three different backgrounds, containing neither SIC1 nor the Cdc6 Cdk-inhibitory domain, in contradiction to previous work. We conclude, therefore, that although both Cdc6 and Sic1 have the potential to facilitate mitotic exit by inhibiting Clb2-Cdk, mitotic exit nevertheless does not require any identified stoichiometric inhibitor of Cdk activity.