Cdc6p-dependent loading of Mcm proteins onto pre-replicative chromatin in budding yeast
Cdc6p-dependent loading of Mcm proteins onto pre-replicative chromatin in budding yeast
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DOI：
10.1073/pnas.94.11.5611
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发表时间：
1997-05-27
影响因子：
11.1
通讯作者：
Diffley, JFX
中科院分区：
文献类型：
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作者：
Donovan, S;Harwood, J;Diffley, JFX
Cdc 6蛋白对于芽殖酵母酿酒酵母中DNA复制起点处的复制前复合物（pre-RC）的组装是必需的，该反应在体内被细胞周期蛋白依赖性激酶Cdc 28 p及其调节亚基、存在于整个S、G（2）和M期的B型细胞周期蛋白阻断，由于B型细胞周期蛋白的破坏和随后激酶的失活对于退出有丝分裂是必不可少的，因此前RC形成只能在通过有丝分裂后发生，因此，已经提出前RC形成对于偶联S期和有丝分裂以及将DNA复制限制在每个细胞周期一次是必需的，Mcm 2 -7蛋白家族在用非洲爪蟾卵提取物进行的实验中，在这里，我们表明，芽殖酵母的Mcm蛋白是丰富的，并定量发现在一个染色质富集的馏分，特别是在G（1）期的细胞周期。这种染色质结合依赖于Cdc 6p的从头合成，提供了证据表明保守的生化途径在酵母和高等真核生物中协调DNA复制与有丝分裂中起着关键作用。Cdc 6p和起源识别复合物可以选择性地从该染色质富集的级分中去除而不去除Mcm蛋白。从这些结果，我们提出Cdc 6p（和起源识别复合物）使Mcm蛋白与染色质的结合成核，但是一旦结合，Mcm蛋白似乎与染色质的一些其他组分紧密地相互作用。
The Cdc6 protein is essential for the assembly of pre-replicative complexes (pre-RCs) at origins of DNA replication in the budding yeast Saccharomyces cerevisiae, This reaction is blocked in vivo by the cyclin-dependent kinase Cdc28p, together with its regulatory subunits, the B type cyclins that are present throughout S, G(2), and M phases, Because the destruction of B type cyclins and the consequent inactivation of the kinase are essential for exit from mitosis, pre-RC formation can only occur after passage through mitosis, Therefore, pre-RC formation has been proposed to be essential for coupling S phase and mitosis and for limiting DNA replication to once per cell cycle, The Mcm2-7 family of proteins has been implicated in limiting replication to once per cell cycle from experiments with Xenopus egg extracts, Here we show that the Mcm proteins of budding yeast are abundant and are quantitatively found in a chromatin-enriched fraction specifically during the G(1) phase of the cell cycle. This chromatin binding depends on the de novo synthesis of Cdc6p, providing evidence that a conserved biochemical pathway plays a critical role in coordinating DNA replication with mitosis in both yeast and higher eukaryotes. Cdc6p and the origin recognition complex can be selectively removed from this chromatin-enriched fraction without removing the Mcm proteins, From these results, we propose that Cdc6p (and the origin recognition complex) nucleates the binding of Mcm proteins to chromatin, but once bound, the Mcm proteins appear to interact tightly with some other component of chromatin.