Rum1 and Cdc18 link inhibition of cyclin-dependent kinase to the initiation of DNA replication in Schizosaccharomyces pombe
Rum1 and Cdc18 link inhibition of cyclin-dependent kinase to the initiation of DNA replication in Schizosaccharomyces pombe
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DOI：
10.1101/gad.10.5.541
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发表时间：
1996-03-01
影响因子：
10.5
通讯作者：
Kelly, TJ
中科院分区：
文献类型：
--
作者：
Jallepalli, PV;Kelly, TJ
真核细胞已经进化出调节机制，以确保DNA复制和有丝分裂的严格交替。最近的工作表明，有丝分裂形式的细胞周期蛋白依赖性激酶（Cdc 2/细胞周期蛋白B）有防止有丝分裂前的基因组再复制的作用，但这种抑制的相关目标是未知的。在这份报告中，我们提出的证据表明，有丝分裂细胞周期蛋白依赖性激酶影响DNA复制，通过抑制积累和功能的Cdc 18，一个关键的调节S期进入。我们发现rum 1（+）基因有效地抑制了条件cdc 18突变体的致死性。相反，Rum 1（+）的缺失增加了cdc 18突变表型的严重性，导致不适当的细胞分裂和活力的快速丧失。生化实验表明，Rum 1通过直接与Cdc 2/细胞周期蛋白B复合物相互作用而有效地抑制组蛋白H1或Cdc 18融合蛋白的Cdc 2磷酸化。Rum 1在促进基因组再复制的条件下过表达诱导Cdc 18蛋白通过主要的转录后机制显著积累。SIC 1是一种与芽殖酵母无关的细胞周期蛋白依赖性激酶抑制剂，其过表达会导致Cdc 18类似的积累，并导致重新复制。我们的数据将Cdc 2激酶的有效抑制剂与启动DNA复制所需的关键蛋白联系起来，并强烈表明细胞周期蛋白依赖性激酶对Cdc 18的抑制在确保基因组在每个细胞周期中精确复制方面具有重要作用。
Eukaryotic cells have evolved regulatory mechanisms to ensure the strict alternation of DNA replication and mitosis. Recent work has suggested that the mitotic form of cyclin-dependent kinase (Cdc2/cyclin B) has a role in preventing re-replication of the genome before mitosis, but the relevant targets of this inhibition are unknown. In this report we present evidence that the mitotic cyclin-dependent kinase affects DNA replication by inhibiting the accumulation and function of Cdc18, a critical regulator of S-phase entry. We found that the rum1(+) gene efficiently suppresses the lethality of a conditional cdc18 mutant. Conversely, deletion of rum1(+) increases the severity of the cdc18 mutant phenotype, resulting in inappropriate cell division and a rapid loss of viability, Biochemical experiments indicate that Rum1 potently inhibits Cdc2 phosphorylation of histone H1 or a Cdc18 fusion protein by directly interacting with the Cdc2/cyclin B complex. Overexpression of Rum1 under conditions that promote re-replication of the genome induces a striking accumulation of Cdc18 protein by a largely post-transcriptional mechanism. Overexpression of SIC1, an unrelated cyclin-dependent kinase inhibitor from budding yeast, causes a similar accumulation of Cdc18 and also leads to re-replication. Our data link a potent inhibitor of Cdc2 kinase to a key protein required for the initiation of DNA replication and strongly suggest that inhibition of Cdc18 by cyclin-dependent kinases has an important role in ensuring that the genome is duplicated precisely once each cell cycle.