Identification of Clb2 residues required for Swe1 regulation of Clb2-Csc28 in Saccharomyces cerevisiae
Identification of Clb2 residues required for Swe1 regulation of Clb2-Csc28 in Saccharomyces cerevisiae
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DOI：
10.1534/genetics.108.086611
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发表时间：
2008-06-01
期刊：
影响因子：
3.3
通讯作者：
Aparicio, Oscar M.
中科院分区：
文献类型：
--
作者：
Hu, Fangfang;Gan, Yan;Aparicio, Oscar M.
Weel激酶通过抑制细胞周期蛋白依赖性激酶（CDK）的磷酸化来调节细胞周期。真核细胞表达多种CDK，每种CDK具有激酶亚基（Cdk）和调节“细胞周期蛋白”亚基，其在细胞周期的不同阶段起作用以调节不同的过程。细胞周期蛋白赋予CDK-底物相互作用特异性，并且还决定特定CDK是否受Weel影响。调控酵母Weel（Swe 1）抑制与有丝分裂细胞周期蛋白Clb 2相关的Cdc 28（Cdk 1），但不抑制与G期（Cln 1、-2和-3）或S期（Clb 5和-6）细胞周期蛋白相关的Cdc 28（Cdk 1）。在这里，我们表明，这种特异性依赖于两个氨基酸与一个保守的“疏水补丁”（HP）基序的细胞周期蛋白表面，介导特异性的CDK-底物相互作用。Clb 2中N260和K270残基的突变在很大程度上消除了Swel对Clb 2-Cdc 28的调控，而Clb 5中相应残基的相互突变则使Clb 5-Cdc 28受到Swel的调控。被认为激活Swel激酶的Clb 2-Cdc 28对Swel的磷酸化依赖于N260和K270，这表明Swel对Clb 2-Cdc 28的特异性调节源自Clb 2靶向Swel以激活磷酸化的特异性能力。Swel 1与Clb 2-Cdc 28的稳定结合也依赖于这些残基，这表明Swel除了通过酪氨酸磷酸化作为CDK活性的调节剂的众所周知的功能之外，还可以竞争性地抑制Clb 2-Cdc 28与底物的相互作用。
Weel kinases regulate the cell cycle through inhibitory phosphorylation of cyclin-dependent kinases (CDKs). Eukaryotic cells express multiple CDKs, each having a kinase subunit (Cdk) and a regulatory "cyclin" subunit that function at different stages of the cell cycle to regulate distinct processes. The cyclin imparts specificity to CDK-substrate interactions and also determines whether a particular CDK is subject to Weel. regulation. Saccharomyces Weel (Swe1) inhibits Cdc28 (Cdk1) associated with the mitotic cyclin, Clb2, but not with the G, (Cln1, -2, and -3) or the S-phase (Clb5 and -6) cyclins. Here, we show that this specificity depends on two amino acids associated with a conserved "hydrophobic patch" (HP) motif on the cyclin surface, which mediates specificity of CDK-substrate interactions. Mutation of Clb2 residues N260 and K270 largely abrogates Clb2-Cdc28 regulation by Swe1, and reciprocal mutation of the corresponding residues in Clb5 can Subject Clb5-Cdc28 to regulation by Swel. Swel phosphorylation by Clb2-Cdc28, which is thought to activate Swel kinase, depends on N260 and K270, suggesting that specific regulation of Clb2-Cdc28 by Swel derives from the specific ability of Clb2 to target Swel for activating phosphorylation. The stable association of Swe1 with Clb2-Cdc28 also depends on these residues, suggesting that Swel may competitively inhibit Clb2-Cdc28 interactions with substrates, in addition to its well-known function as a regulator of CDK activity through tyrosine phosphorylation.