Checkpoint kinase 2 (Chk2) inhibits the activity of the Cdc45/MCM2-7/GINS (CMG) replicative helicase complex
Checkpoint kinase 2 (Chk2) inhibits the activity of the Cdc45/MCM2-7/GINS (CMG) replicative helicase complex
复制标题
DOI：
10.1073/pnas.1211525109
复制
发表时间：
2012-08-14
影响因子：
11.1
通讯作者：
Botchan, Michael R.
中科院分区：
文献类型：
--
作者：
Ilves, Ivar;Tamberg, Nele;Botchan, Michael R.
当DNA受损时，真核生物染色体的复制会减慢，并且在分叉处工作的蛋白质（复制体）是介导这种反应的信号通路的已知靶点，这种反应对于准确的基因组遗传至关重要。然而，这种反应是如何介导的分子机制和细节知之甚少。在这份报告中，我们表明，复制体解旋酶的活性，Cdc 45/MCM 2 -7/GINS（CMG）复合物，可以抑制蛋白磷酸化。重组果蝇CMG可以通过磷酸酶处理而刺激，而Chk 2，而不是Chk 1在体外干扰解旋酶活性。Chk 2磷酸化的靶标已经被鉴定，并且存在于MCM亚基3和4以及GINS蛋白Psf 2中。干扰需要结合修改，我们认为，负电荷的形成可能会创建一个表面上的解旋酶变构影响其功能。用电离辐射处理发育中的苍蝇胚胎导致活性解旋酶复合物中Psf 2亚基的过度磷酸化。总之，这些数据表明，由Chk 2的CMG解旋酶的直接修饰是响应DNA损伤的重要联系。
The replication of eukaryote chromosomes slows down when DNA is damaged and the proteins that work at the fork (the replisome) are known targets for the signaling pathways that mediate such responses critical for accurate genomic inheritance. However, the molecular mechanisms and details of how this response is mediated are poorly understood. In this report we show that the activity of replisome helicase, the Cdc45/MCM2-7/GINS (CMG) complex, can be inhibited by protein phosphorylation. Recombinant Drosophila melanogaster CMG can be stimulated by treatment with phosphatase whereas Chk2 but not Chk1 interferes with the helicase activity in vitro. The targets for Chk2 phosphorylation have been identified and reside in MCM subunits 3 and 4 and in the GINS protein Psf2. Interference requires a combination of modifications and we suggest that the formation of negative charges might create a surface on the helicase to allosterically affect its function. The treatment of developing fly embryos with ionizing radiation leads to hyperphosphorylation of Psf2 subunit in the active helicase complex. Taken together these data suggest that the direct modification of the CMG helicase by Chk2 is an important nexus for response to DNA damage.