Identification of stimulators and inhibitors of Cdc7 kinase in vitro
Identification of stimulators and inhibitors of Cdc7 kinase in vitro
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DOI：
10.1074/jbc.m803113200
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发表时间：
2008-07-11
影响因子：
4.8
通讯作者：
Masai, Hisao
中科院分区：
文献类型：
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作者：
Kakusho, Naoko;Taniyama, Chika;Masai, Hisao
Cdc 7是一种丝氨酸-苏氨酸激酶，调节DNA复制的起始和进展。纯化的Cdc 7激酶的活性被多胺如精胺或亚精胺显著刺激。带正电的赖氨酸或精氨酸聚合物也会刺激其激酶活性，而带负电的物质（例如聚谷氨酸或核酸）会显着抑制激酶活性。精胺影响Cdc 7激酶对微小染色体维持（MCM）底物的Km和V-max。我们还发现，组蛋白，赖氨酸和甘氨酸丰富的碱性蛋白质，可以刺激Cdc 7激酶活性，并与组蛋白的MCM复合物是一个更有效的基板Cdc 7比自由MCM复合物。这些结果确定了潜在的细胞抑制剂和刺激剂的Cdc 7激酶，并建议Cdc 7可能是另一个目标的细胞多胺和组蛋白可能会刺激Cdc 7介导的磷酸化染色质结合底物。异位表达的抗酶，已知降低细胞多胺水平，导致Cdc 7介导的MCM 4蛋白磷酸化的减少，表明多胺在调节Cdc 7激酶活性的细胞中的生理作用。
Cdc7 is a serine-threonine kinase that regulates initiation and progression of DNA replication. The activity of purified Cdc7 kinase is significantly stimulated by polyamines such as spermine or spermidine. Positively charged polymers of lysine or arginine also stimulate its kinase activity, whereas the negatively charged substances such as polyglutamate or nucleic acids significantly inhibit the kinase activity. Spermine affects both the K-m and V-max of Cdc7 kinase for a minichromosome maintenance (MCM) substrate. We also found that histones, lysine- and arginine-rich basic proteins, can stimulate Cdc7 kinase activity, and a MCM complex in association with histone is a more efficient substrate of Cdc7 than the free MCM complex. These results identify potential cellular inhibitors and stimulators of Cdc7 kinase and suggest that Cdc7 may be another target of cellular polyamines and that histones may stimulate Cdc7-mediated phosphorylation of chromatin-bound substrates. Ectopic expression of an antizyme, known to reduce the cellular polyamine levels, resulted in reduction of Cdc7-mediated phosphorylation of MCM4 protein, suggesting physiological roles of polyamines in regulation of Cdc7 kinase activity in the cells.