Conversion of DNA gyrase into a conventional type II topoisomerase
Conversion of DNA gyrase into a conventional type II topoisomerase
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DOI：
10.1073/pnas.93.25.14416
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发表时间：
1996-12-10
影响因子：
11.1
通讯作者：
Maxwell, A
中科院分区：
文献类型：
--
作者：
Kampranis, SC;Maxwell, A
在拓扑异构酶中，DNA旋转酶具有将负超螺旋引入闭合环状DNA的能力。我们已经证明，缺失促旋酶的A亚基的C-末端DNA结合结构域产生不能超螺旋DNA但以ATP依赖性方式松弛DNA的酶。新生霉素是促旋酶结合ATP的竞争性抑制剂，可抑制该反应。与促旋酶不同，截短的酶在与DNA结合时不引入右手缠绕，并稳定DNA交换;特征让人想起传统的II型拓扑异构酶。与完整的促旋酶相比，这种新的酶形式可以以增加的效率使DNA环解链，因此，可以补充parC（ts）突变体的温度敏感表型。因此，这些结果表明，DNA促旋酶的独特性质是由于周围的A亚基的C-末端DNA结合结构域的DNA的包装，并提供了一个洞察II型拓扑异构酶的机制。
DNA gyrase is unique among topoisomerases in its ability to introduce negative supercoils into closed-circular DNA. We have demonstrated that deletion of the C-terminal DNA-binding domain of the A subunit of gyrase gives rise to an enzyme that cannot supercoil DNA but relaxes DNA in an ATP-dependent manner. Novobiocin, a competitive inhibitor of ATP binding by gyrase, inhibits this reaction. The truncated enzyme, unlike gyrase, does not introduce a right-handed wrap when bound to DNA and stabilizes DNA crossovers; characteristics reminiscent of conventional type II topoisomerases. This new enzyme form can decatenate DNA circles with increased efficiency compared with intact gyrase and, as a result, can complement the temperature-sensitive phenotype of a parC(ts) mutant. Thus these results suggest that the unique properties of DNA gyrase are attributable to the wrapping of DNA around the C-terminal DNA-binding domains of the A subunits and provide an insight into the mechanism of type II topoisomerases.