Mechanism of topology simplification by type II DNA topoisomerases
Mechanism of topology simplification by type II DNA topoisomerases
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DOI：
10.1073/pnas.061029098
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发表时间：
2001-03-13
影响因子：
11.1
通讯作者：
Cozzarelli, NR
中科院分区：
文献类型：
--
作者：
Vologodskii, AV;Zhang, WT;Cozzarelli, NR
II型DNA拓扑异构酶主动减少打结和链状环状DNA的分数低于热力学平衡值。为了解释这一惊人的发现，我们设计了一个模型，在这个模型中，拓扑异构酶在DNA中引入了一个尖锐的弯曲。因为酶相对于弯曲有一个特定的方向，它们就像麦克斯韦的恶魔，提供单向的链通道。通过计算机模拟对模型进行定量分析，证明该模型可以解释大量的实验数据。所需的尖锐的DNA弯曲证明了大大增加的环化短DNA片段的拓扑异构酶结合和直接可视化与电子显微镜。
Type II DNA topoisomerases actively reduce the fractions of knotted and catenated circular DNA below thermodynamic equilibrium values. To explain this surprising finding, we designed a model in which topoisomerases introduce a sharp bend in DNA. Because the enzymes have a specific orientation relative to the bend, they act like Maxwell's demon, providing unidirectional strand passage. Quantitative analysis of the model by computer simulations proved that it can explain much of the experimental data. The required sharp DNA bend was demonstrated by a greatly increased cyclization of short DNA fragments from topoisomerase binding and by direct visualization with electron microscopy.