Two mechanisms coordinate replication termination by the Escherichia coli Tus-Ter complex.
Two mechanisms coordinate replication termination by the Escherichia coli Tus-Ter complex.
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DOI：
10.1093/nar/gkv527
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发表时间：
2015-07-13
影响因子：
14.9
通讯作者：
Patel SS
中科院分区：
文献类型：
--
作者：
Pandey M;Elshenawy MM;Jergic S;Takahashi M;Dixon NE;Hamdan SM;Patel SS
大肠杆菌复制终止蛋白 (Tus) 与 Ter 序列结合，阻止复制叉从一个方向接近。在这里，我们使用单分子和瞬态动力学来研究异源噬菌体 T7 复制体对 Tus-Ter 复合物的反应。 T7 复制体以复合捕鼠器和动态钳模型解释的方式被捕获在 Tus-Ter 的非允许端。未配对的 C(6) 通过结合到 Tus 的胞嘧啶结合口袋中形成锁，在阻止复制体方面最有效，而 C(6) 的突变则消除了屏障。分离的解旋酶也在非允许端被阻断，但出乎意料的是，分离的聚合酶并未被阻断，除非 C(6) 未配对。相反，聚合酶在许可端被阻断。这表明 Tus-Ter 机制对 DNA 马达的易位极性敏感。沿着模板链追踪的聚合酶捕获 C(6) 以防止锁形成；沿着另一条链的解旋酶捕获互补的 G(6) 以帮助锁的形成。我们的结果与模型一致，其中解旋酶的链分离使 GC(6) 碱基对不成对，并在聚合酶隔离 C(6) 碱基之前立即触发锁形成。
The Escherichia coli replication terminator protein (Tus) binds to Ter sequences to block replication forks approaching from one direction. Here, we used single molecule and transient state kinetics to study responses of the heterologous phage T7 replisome to the Tus–Ter complex. The T7 replisome was arrested at the non-permissive end of Tus–Ter in a manner that is explained by a composite mousetrap and dynamic clamp model. An unpaired C(6) that forms a lock by binding into the cytosine binding pocket of Tus was most effective in arresting the replisome and mutation of C(6) removed the barrier. Isolated helicase was also blocked at the non-permissive end, but unexpectedly the isolated polymerase was not, unless C(6) was unpaired. Instead, the polymerase was blocked at the permissive end. This indicates that the Tus–Ter mechanism is sensitive to the translocation polarity of the DNA motor. The polymerase tracking along the template strand traps the C(6) to prevent lock formation; the helicase tracking along the other strand traps the complementary G(6) to aid lock formation. Our results are consistent with the model where strand separation by the helicase unpairs the GC(6) base pair and triggers lock formation immediately before the polymerase can sequester the C(6) base.
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影响因子：
64.5
作者：
Mulcair, Mark D.;Schaeffer, Patrick M.;Dixon, Nicholas E.
通讯作者：
Dixon, Nicholas E.
影响因子：
14.9
作者：
Cavaluzzi, MJ;Borer, PN
通讯作者：
Borer, PN
DOI：
10.1073/pnas.87.7.2481
发表时间：
1990-04-01
影响因子：
11.1
作者：
HILL, TM;MARIANS, KJ
通讯作者：
MARIANS, KJ
影响因子：
4.8
作者：
CoskunAri, FF;Hill, TM
通讯作者：
Hill, TM
影响因子：
64.8
作者：
Lee, JB;Hite, RK;van Oijen, AM
通讯作者：
van Oijen, AM