CDK-dependent phosphorylation of Sld2 and Sld3 initiates DNA replication in budding yeast
CDK-dependent phosphorylation of Sld2 and Sld3 initiates DNA replication in budding yeast
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DOI：
10.1038/nature05465
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发表时间：
2007-01-18
期刊：
影响因子：
64.8
通讯作者：
Araki, Hiroyuki
中科院分区：
文献类型：
--
作者：
Tanaka, Seiji;Umemori, Toshiko;Araki, Hiroyuki
在真核细胞中，细胞周期蛋白依赖性激酶（CDK）在细胞周期的各个点都有重要的参与。在S期开始时，活性CDK对于染色体DNA复制是必不可少的（1），尽管其确切作用尚不清楚。在芽殖酵母（酿酒酵母）中，复制蛋白Sld 2（参考文献2）是一种必需的CDK底物（3），但其磷酸模拟物形式（Sld 2 - 11 D）单独既不影响细胞生长（4），也不促进缺乏CDK活性的DNA复制（4），这表明其他必需的CDK底物促进DNA复制。在这里，我们表明，CDC 45（JET 1）和高拷贝DPB 11的等位基因，结合Sld 2 - 11 D，分别赋予CDK独立的DNA复制。虽然Cdc 45不是必需的CDK底物，但与Cdc 45相关的Sld 3的CDK依赖性磷酸化是必需的，并产生Dpb 11的结合位点。JET 1突变和高拷贝DPB 11都绕过了DNA复制中Sld 3磷酸化的要求。由于磷酸化的Sld 2与Dpb 11中BRCT结构域的羧基末端对结合（参考文献4），我们认为Dpb 11连接磷酸化的Sld 2和Sld 3，以促进复制蛋白（如Cdc 45和GINS）之间的相互作用。我们的研究结果表明，CDKs调节BRCT结构域的复制蛋白和其他磷酸化蛋白质之间的相互作用，启动染色体DNA复制，类似的调节可能发生在高等真核生物。
In eukaryotic cells, cyclin-dependent kinases (CDKs) have an important involvement at various points in the cell cycle. At the onset of S phase, active CDK is essential for chromosomal DNA replication(1), although its precise role is unknown. In budding yeast ( Saccharomyces cerevisiae), the replication protein Sld2 (ref. 2) is an essential CDK substrate(3), but its phospho-mimetic form (Sld2-11D) alone neither affects cell growth(4) nor promotes DNA replication in the absence of CDK activity(4), suggesting that other essential CDK substrates promote DNA replication. Here we show that both an allele of CDC45 (JET1) and high-copy DPB11, in combination with Sld2-11D, separately confer CDK-independent DNA replication. Although Cdc45 is not an essential CDK substrate, CDK-dependent phosphorylation of Sld3, which associates with Cdc45 ( ref. 5), is essential and generates a binding site for Dpb11. Both the JET1 mutation and high-copy DPB11 by-pass the requirement for Sld3 phosphorylation in DNA replication. Because phosphorylated Sld2 binds to the carboxy-terminal pair of BRCT domains in Dpb11 ( ref. 4), we propose that Dpb11 connects phosphorylated Sld2 and Sld3 to facilitate interactions between replication proteins, such as Cdc45 and GINS. Our results demonstrate that CDKs regulate interactions between BRCT-domain-containing replication proteins and other phosphorylated proteins for the initiation of chromosomal DNA replication; similar regulation may take place in higher eukaryotes.