Negative regulation of condensin I by CK2‐mediated phosphorylation
Negative regulation of condensin I by CK2‐mediated phosphorylation
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DOI：
10.1038/sj.emboj.7601394
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发表时间：
2006-11
期刊：
影响因子：
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通讯作者：
Ai Takemoto;K. Kimura;J. Yanagisawa;S. Yokoyama;F. Hanaoka
中科院分区：
文献类型：
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作者：
Ai Takemoto;K. Kimura;J. Yanagisawa;S. Yokoyama;F. Hanaoka
凝聚素I在体内有丝分裂染色体组装和分离中起重要作用，在体外三磷酸腺苷存在下，它将正超螺旋限制在DNA中。凝聚蛋白I是组成性存在于整个HeLa细胞周期的磷酸化形式，但在其被磷酸化在间期细胞的网站不同的有丝分裂过程中所识别的Cdc2。免疫耗竭、体外磷酸化和使用磷酸特异性抗体的免疫印迹分析表明，CK2激酶可能是间期凝结蛋白I磷酸化的原因。与Cdc2诱导的凝聚素I磷酸化对超螺旋的轻微刺激作用相反，CK2的磷酸化降低了凝聚素I的超螺旋活性。CK 2介导的凝聚素I磷酸化在空间和时间上的调节方式与Cdc 2介导的磷酸化不同：CK 2依赖的磷酸化在间期增加，在有丝分裂期间在染色体上减少。这些研究结果是第一次证明了一个负调控模式的凝聚素I，一个过程，可能会影响染色质结构在间期和有丝分裂。
Condensin I, which plays an essential role in mitotic chromosome assembly and segregationin vivo, constrains positive supercoils into DNA in the presence of adenosine triphosphatein vitro. Condensin I is constitutively present in a phosphorylated form throughout the HeLa cell cycle, but the sites at which it is phosphorylated in interphase cells differ from those recognized by Cdc2 during mitosis. Immunodepletion,in vitrophosphorylation, and immunoblot analysis using a phospho‐specific antibody suggested that the CK2 kinase is likely to be responsible for phosphorylation of condensin I during interphase. In contrast to the slight stimulatory effect of Cdc2‐induced phosphorylation of condensin I on supercoiling, phosphorylation by CK2 reduced the supercoiling activity of condensin I. CK2‐mediated phosphorylation of condensin I is spatially and temporally regulated in a manner different to that of Cdc2‐mediated phosphorylation: CK2‐dependent phosphorylation increases during interphase and decreases on chromosomes during mitosis. These findings are the first to demonstrate a negative regulatory mode for condensin I, a process that may influence chromatin structure during interphase and mitosis.