Repression of nascent strandelongation by deregulated Cdt1 during DNA replication in Xenopus egg extracts
Repression of nascent strandelongation by deregulated Cdt1 during DNA replication in Xenopus egg extracts
复制标题
非洲爪蟾卵提取物 DNA 复制过程中 Cdt1 失调对新生链延伸的抑制
DOI：
10.1091/mbc.e08-06-0613
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
S.
中科院分区：
文献类型：
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作者：
Tsuyama;T.;Watanabe;S.;Aoki;A.;Cho;Y.;Seki;M.;Enomoto;T. and Tada;S.
过量Cdt 1据报道诱导再复制的染色质在培养的细胞和Xenopusegg提取物，表明Cdt 1活性的调节细胞周期依赖性蛋白水解和表达的Cdt 1抑制剂geminin是至关重要的抑制染色体过度复制之间的S期和中期。我们分析了过量Cdt 1对DNA复制的影响，发现Cdt 1活性的增加抑制了Xenopusegg提取物中新生链的伸长。在补充Cdt 1的提取物中，进一步添加缺乏许可抑制剂活性的双子蛋白（Gem 79 -130）的Cdt 1结合结构域显着诱导过度复制。进一步的分析表明，完全活跃的双生蛋白，以及Gem 79 -130，恢复新生链伸长Cdt 1补充提取物，即使Cdt 1诱导的停滞复制叉伸长已经建立。我们的研究结果表明，Cdt 1在延长一个不可预见的，负面的作用，并建议其在复制控制功能应重新定义。我们提出了一种新的监视机制，其中Cdt 1块新生链伸长后，检测非法激活的许可证制度。
Excess Cdt1 reportedly induces rereplication of chromatin in cultured cells andXenopusegg extracts, suggesting that the regulation of Cdt1 activity by cell cycle-dependent proteolysis and expression of the Cdt1 inhibitor geminin is crucial for the inhibition of chromosomal overreplication between S phase and metaphase. We analyzed the consequences of excess Cdt1 for DNA replication and found that increased Cdt1 activity inhibited the elongation of nascent strands inXenopusegg extracts. In Cdt1-supplemented extracts, overreplication was remarkably induced by the further addition of the Cdt1-binding domain of geminin (Gem79-130), which lacks licensing inhibitor activity. Further analyses indicated that fully active geminin, as well as Gem79-130, restored nascent strand elongation in Cdt1-supplemented extracts even after the Cdt1-induced stalling of replication fork elongation had been established. Our results demonstrate an unforeseen, negative role for Cdt1 in elongation and suggest that its function in the control of replication should be redefined. We propose a novel surveillance mechanism in which Cdt1 blocks nascent chain elongation after detecting illegitimate activation of the licensing system.