Tethered particle motion reveals that LacI·DNA loops coexist with a competitor-resistant but apparently unlooped conformation.
Tethered particle motion reveals that LacI·DNA loops coexist with a competitor-resistant but apparently unlooped conformation.
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束缚粒子运动揭示了 LacI·DNA 环与竞争者抗性但明显未成环的构象共存。
DOI：
10.1016/j.bpj.2013.12.024
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发表时间：
2014
影响因子：
3.4
通讯作者：
Meiners,Jens-Christian
中科院分区：
文献类型：
--
作者：
Revalee,JoelD;Blab,GerhardA;Wilson,HenryD;Kahn,JasonD;Meiners,Jens-Christian
Lac抑制蛋白(Lac Repressor Protein，LacI)通过与细菌DNA上两个距离较远的操纵子结合，使其间的DNA形成环状，从而有效地抑制大肠杆菌中Lac操纵子的转录。我们使用单分子拴系粒子运动来观察LacI介导的环的形成和DNA结构中的破坏，这些结构包含了优化的操作符结合位点和有利于环形成的本征曲率。以前的批量竞争分析间接测量了这些优化DNA结构中的环寿命约为几天；然而，我们测量了环和非环状态的相同寿命约为几分钟。在一系列单分子DNA竞争实验中，我们发现LacI-DNA复合体对竞争结合的抗性是操纵子强度和操纵子间序列的函数。为了解释这些发现，我们提出了一个我们认为是环形成和DNA竞争的新动力学模型。在这个新的模型中，我们假设了一种新的非环状状态，在这种状态下，LacI蛋白的未结合DNA结合域与第二个LacI DNA结合域结合的操纵子位点附近的非操纵子DNA非特异性地相互作用。
The lac repressor protein (LacI) efficiently represses transcription of the lac operon inEscherichia coliby binding to two distant operator sites on the bacterial DNA and causing the intervening DNA to form a loop. We employed single-molecule tethered particle motion to observeLacI-mediated loop formation and breakdown in DNA constructs that incorporate optimized operator binding sites and intrinsic curvature favorable to loop formation. Previous bulk competition assays indirectly measured the loop lifetimes in these optimized DNA constructs as being on the order of days; however, we measured these same lifetimes to be on the order of minutes for both looped and unlooped states. In a range of single-molecule DNA competition experiments, we found that the resistance of theLacI-DNA complex to competitive binding is a function of both the operator strength and the interoperator sequence. To explain these findings, we present what we believe to be a new kinetic model of loop formation and DNA competition. In this proposed new model, we hypothesize a new unlooped state in which the unbound DNA-binding domain of theLacI protein interacts nonspecifically with nonoperator DNA adjacent to the operator site at which the secondLacI DNA-binding domain is bound.
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影响因子：
3.4
作者：
Manzo, Carlo;Zurla, Chiara;Finzi, Laura
通讯作者：
Finzi, Laura
Lacl DNA 结合域变体 Nlac-P 的模拟动力学与实验测定动力学的比较。
影响因子：
3.4
作者：
Swint-Kruse,L;Matthews,KS;Smith,PE;Pettitt,BM
通讯作者：
Pettitt,BM
lac阻遏物与携带两个适当间隔的lac操纵子的线性DNA形成环。
影响因子：
11.4
作者：
Helmut Kramer;Monika Niemoller;Michele Amouyall;Bernard Revet;B. Wilcken;B. Muller
通讯作者：
B. Muller
DOI：
10.1073/pnas.0409387102
发表时间：
2005-05
影响因子：
11.1
作者：
E. Villa;A. Balaeff;K. Schulten
通讯作者：
E. Villa;A. Balaeff;K. Schulten
LAC阻遏铰链柔韧性和DNA循环：通过束缚颗粒运动的单分子动力学。
影响因子：
14.9
作者：
Vanzi, Francesco;Broggio, Chiara;Sacconi, Leonardo;Pavone, Francesco Saverio
通讯作者：
Pavone, Francesco Saverio