EUKARYOTIC TOPOISOMERASES RECOGNIZE NUCLEIC-ACID TOPOLOGY BY PREFERENTIALLY INTERACTING WITH DNA CROSSOVERS
EUKARYOTIC TOPOISOMERASES RECOGNIZE NUCLEIC-ACID TOPOLOGY BY PREFERENTIALLY INTERACTING WITH DNA CROSSOVERS
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DOI：
10.1002/j.1460-2075.1990.tb07908.x
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发表时间：
1990-12-01
期刊：
影响因子：
11.4
通讯作者：
OSHEROFF, N
中科院分区：
文献类型：
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作者：
ZECHIEDRICH, EL;OSHEROFF, N
真核生物拓扑异构酶识别DNA拓扑结构，并优先与放松底物上的正或负超旋分子反应。为了阐明这种识别的机制，我们通过电子显微镜检查了拓扑异构酶与DNA的相互作用。在所有使用的条件下，大约90%的结合型I或II酶在负超旋质粒上的螺旋-螺旋并置点上被观察到，这些负超旋质粒只含有4个交叉。识别与扭转应力无关，因为在线性DNA的交叉处也发现了酶分子。由于与松弛核酸相比，并置螺旋在超卷曲核酸中更为普遍，我们提出真核拓扑异构酶I和II通过优先与DNA交叉作用来识别欠缠绕或过缠绕的底物。这可能代表了蛋白质识别DNA拓扑结构的一般机制。
Eukaryotic topoisomerases recognize DNA topology and preferentially react with positively or negatively supercoiled molecules over relaxed substrates. To elucidate the mechanism of this recognition, we examined the interaction of topoisomerases with DNA by electron microscopy. Under all conditions employed, approximately 90% of the bound type I or II enzyme was observed at points of helix - helix juxtaposition on negatively supercoiled plasmids which contained as few as four crossovers. Recognition was independent of torsional stress, as enzyme molecules were also found at crossovers on linear DNA. Since juxtaposed helices are more prevalent in supercoiled compared with relaxed nucleic acids, we propose that eukaryotic topoisomerases I and II recognize underwound or overwound substrates by interacting preferentially with DNA crossovers. This may represent a general mechanism for the recognition of DNA topology by proteins.