Highly stable loading of Mcm proteins onto chromatin in living cells requires replication to unload.
Highly stable loading of Mcm proteins onto chromatin in living cells requires replication to unload.
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DOI：
10.1083/jcb.201007111
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发表时间：
2011-01-10
期刊：
影响因子：
--
通讯作者：
Gilbert DM
中科院分区：
文献类型：
--
作者：
Kuipers MA;Stasevich TJ;Sasaki T;Wilson KA;Hazelwood KL;McNally JG;Davidson MW;Gilbert DM
微小染色体维持复合物（Mcm 2 -7）的成分在G1期和复制停滞期间保持与染色质无限期结合。异源六聚体微小染色体维持蛋白复合物（Mcm 2 -7）在DNA复制过程中作为真核解旋酶发挥功能。Mcm 2 -7在G1期早期加载到染色质上，但直到S期很晚才转化为活性解旋酶。因此，推测无活性的Mcm复合物从G1早期到S期完成保持稳定结合。在这里，我们研究了活的哺乳动物细胞中的Mcm蛋白动力学。我们证明，Mcm蛋白不可逆地加载到染色质上累积整个G1期，显示没有检测到的交换与逐渐减少的可溶性池。驱逐Mcm需要复制;在复制停滞期间，Mcm蛋白质无限期地保持结合。此外，不动的MCMS的密度减少连同活性复制的位点内的染色质去凝聚，这提供了一个解释，缺乏与复制叉蛋白的共定位的MCM。这些结果提供了异常稳定的锁定机制的体内证据，以在整个延长的细胞周期中将所有负载的Mcm蛋白保留在染色质上。
Components of the minichromosome maintenance complex (Mcm2-7) remain indefinitely bound to chromatin during G1 phase and replication arrest. The heterohexameric minichromosome maintenance protein complex (Mcm2-7) functions as the eukaryotic helicase during DNA replication. Mcm2-7 loads onto chromatin during early G1 phase but is not converted into an active helicase until much later during S phase. Hence, inactive Mcm complexes are presumed to remain stably bound from early G1 through the completion of S phase. Here, we investigated Mcm protein dynamics in live mammalian cells. We demonstrate that Mcm proteins are irreversibly loaded onto chromatin cumulatively throughout G1 phase, showing no detectable exchange with a gradually diminishing soluble pool. Eviction of Mcm requires replication; during replication arrest, Mcm proteins remained bound indefinitely. Moreover, the density of immobile Mcms is reduced together with chromatin decondensation within sites of active replication, which provides an explanation for the lack of colocalization of Mcm with replication fork proteins. These results provide in vivo evidence for an exceptionally stable lockdown mechanism to retain all loaded Mcm proteins on chromatin throughout prolonged cell cycles.
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DOI：
10.1083/jcb.153.7.1341
发表时间：
2001-06-25
期刊：
The Journal of cell biology
影响因子：
--
作者：
Kimura H;Cook PR
通讯作者：
Cook PR
DOI：
10.1073/pnas.061487598
发表时间：
2001-03-13
影响因子：
11.1
作者：
DaFonseca, CJ;Shu, F;Zhang, JJ
通讯作者：
Zhang, JJ
DOI：
10.1073/pnas.1332608100
发表时间：
2003-06-24
影响因子：
11.1
作者：
de Boer, E;Rodriguez, P;Strouboulis, J
通讯作者：
Strouboulis, J
影响因子：
4
作者：
Ferguson, Rebecca L.;Maller, James L.
通讯作者：
Maller, James L.
DOI：
10.1073/pnas.0911500106
发表时间：
2009-12-01
影响因子：
11.1
作者：
Evrin, Cecile;Clarke, Pippa;Speck, Christian
通讯作者：
Speck, Christian