Simplification of DNA topology below equilibrium values by type II topoisomerases
Simplification of DNA topology below equilibrium values by type II topoisomerases
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DOI：
10.1126/science.277.5326.690
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发表时间：
1997-08-01
期刊：
影响因子：
56.9
通讯作者：
Cozzarelli, NR
中科院分区：
文献类型：
--
作者：
Rybenkov, VV;Ullsperger, C;Cozzarelli, NR
II 型 DNA 拓扑异构酶通过将一个 DNA 片段转运到另一个 DNA 片段来催化 DNA 拓扑异构体的相互转化。发现原核和真核 II 型拓扑异构酶产生的打结或链状 DNA 分子的稳态分数比热力学平衡时低 80 倍。这些酶还产生比平衡时更紧密的连接数拓扑异构体分布。因此，拓扑异构酶不仅催化随机并置的 DNA 片段的通过，而且控制 DNA 的整体特性，即其拓扑结构。结果表明，II 型拓扑异构酶利用三磷酸腺苷水解的能量优先去除为 DNA 分离提供障碍的拓扑连接。
Type II DNA topoisomerases catalyze the interconversion of DNA topoisomers by transporting one DNA segment through another. The steady-state fraction of knotted or catenated DNA molecules produced by prokaryotic and eukaryotic type II topoisomerases was found to be as much as 80 times lower than at thermodynamic equilibrium. These enzymes also yielded a tighter distribution of linking number topoisomers than at equilibrium. Thus, topoisomerases do not merely catalyze passage of randomly juxtaposed DNA segments but control a global property of DNA, its topology. The results imply that type II topoisomerases use the energy of adenosine triphosphate hydrolysis to preferentially remove the topological links that provide barriers to DNA segregation.