DNA breakage and closure by rat liver type 1 topoisomerase: separation of the half-reactions by using a single-stranded DNA substrate.
DNA breakage and closure by rat liver type 1 topoisomerase: separation of the half-reactions by using a single-stranded DNA substrate.
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大鼠肝脏 1 型拓扑异构酶造成的 DNA 断裂和闭合：使用单链 DNA 底物分离半反应。
DOI：
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发表时间：
1981
影响因子：
11.1
通讯作者：
J. Champoux
中科院分区：
文献类型：
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作者：
M. D. Been;J. Champoux
噬菌体phi X174 DNA的环状单链在37 ℃下在低盐（50 mM KCl）中被大鼠肝DNA切口闭合酶（1型拓扑异构酶）断裂，产生含有共价结合酶的线性链[Been，M. D.和Champoux，J.J.（1980）Nucleic Acids Res.8，6129-6142]。线性链可以在24 ℃和37 ℃下在10 mM MgCl 2或24 ℃下在250 mM KCl存在下再环化。当5'末端的羟基被磷酸化时，再循环被阻断。由切口闭合酶产生的线性也可以连接到含有5'羟基但不含5'磷酸的其他DNA片段。链内和链间反应中形成的键对碱稳定。断裂单链的重新闭合被认为类似于双链体DNA上的切口和闭合循环期间发生的闭合步骤。
Circular single strands of bacteriophage phi X174 DNA are broken by rat liver DNA nicking-closing enzyme (type 1 topoisomerase) in low salt (50 mM KCl) at 37 degrees C, generating linear strands containing covalently bound enzyme [Been, M. D. & Champoux, J. J. (1980) Nucleic Acids Res. 8, 6129-6142]. The linear strands can be recircularized in the presence of 10 mM MgCl2 at 24 degrees C and 37 degrees C or 250 mM KCl at 24 degrees C. Recircularization is blocked when the hydroxyl group at the 5' terminus is phosphorylated. The linears generated by the nicking-closing enzyme can also be joined to other DNA fragments containing 5' hydroxyls, but not 5' phosphates. The linkage formed in both the intrastrand and interstrand reactions is stable to alkali. Reclosure of broken single strands is presumed to be analogous to the closure step that occurs durng nicking and closing cycles on duplex DNA.