权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Analysis of the cell cycle regulation of chromosome condensation protein complex, condensin.

染色体凝缩蛋白复合物凝缩蛋白的细胞周期调控分析。

基本信息

批准号：
15370091
负责人：
KIMURA Keiji
金额：
$ 9.66万
依托单位：
RIKEN
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Condensin, a conserved pentameric protein complex composed of SMC heterodimer (SMC2/CAP-E and SMC4/CAP-E) and three other non-SMC subunits (CAP-D2, -G, and -H), plays an essential role in mitotic chromosome condensation in vivo. Condensin induces positive supercoiling into DNA in the presence of topo I using the energy of ATP hydrolysis in vitro. In addition to their mitotic functions, condensins have been implicated in chromatin regulation during interphase, such as DNA repair, damage checkpoint response and transcriptional regulation.We analyzed precisely cell cycle regulation of condensin complex. The protein levels and stabilities of condensin subunits were almost constant throughout the cell cycle. Condensin was phosphorylated by Cdc2 during mitosis, and by CK2 during interphase. In contrast to the 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.When condensin was added into in vitro transcription system, transcription level was reduced, and the suppression was cancelled by the CK2-mediated phosphorylation. Thus, it is possible chromatin structure was compacted by condensin during interphase, and inhibition of condensin activity by the CK2-mediated phosphorylation leads to relaxation of chromatin structure and transactivation.

凝缩蛋白是一种保守的五聚体蛋白复合物，由 SMC 异二聚体（SMC2/CAP-E 和 SMC4/CAP-E）和其他三个非 SMC 亚基（CAP-D2、-G 和 -H）组成，在体内有丝分裂染色体凝缩中发挥重要作用。在拓扑 I 存在的情况下，Condensin 利用体外 ATP 水解的能量诱导正超螺旋形成 DNA。除了有丝分裂功能外，凝缩蛋白还参与间期染色质调节，例如DNA修复、损伤检查点反应和转录调节。我们精确分析了凝缩蛋白复合物的细胞周期调节。凝缩蛋白亚基的蛋白质水平和稳定性在整个细胞周期中几乎恒定。凝缩蛋白在有丝分裂期间被 Cdc2 磷酸化，并在间期期间被 CK2 磷酸化。与 Cdc2 诱导的凝缩蛋白 I 磷酸化对超螺旋的刺激作用相反，CK2 的磷酸化降低了凝缩蛋白 I 的超螺旋活性。CK2 介导的凝缩蛋白 I 磷酸化在空间和时间上的调节方式与 Cdc2 介导的磷酸化不同：CK2 依赖性磷酸化在间期期间增加，在间期期间减少。有丝分裂期间的染色体。这些发现首次证明了凝缩蛋白I的负调控模式，这一过程可能影响间期和有丝分裂期间的染色质结构。当将凝缩蛋白添加到体外转录系统中时，转录水平降低，并且CK2介导的磷酸化消除了抑制。因此，染色质结构可能在间期被凝缩蛋白压缩，CK2介导的磷酸化对凝缩蛋白活性的抑制导致染色质结构松弛和反式激活。