DNA gyrase: site-specific interactions and transient double-strand breakage of DNA.
DNA gyrase: site-specific interactions and transient double-strand breakage of DNA.
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DNA 旋转酶：位点特异性相互作用和 DNA 瞬时双链断裂。
DOI：
10.1101/sqb.1981.045.01.053
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
K. Mizuuchi
中科院分区：
文献类型：
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作者：
M. Gellert;L. Fisher;H. Ohmori;M. H. O'dea;K. Mizuuchi
催化 DNA 磷酸二酯键瞬时断裂和重新连接的酶在自然界中广泛存在。在某些情况下，它们最初被鉴定为拓扑异构酶，如此命名是因为它们能够介导DNA拓扑异构体的相互转化（例如，通过去除或引入超螺旋转角）。对于所有拓扑异构酶，DNA 的断裂似乎与共价连接的酶-DNA 中间体的形成有关，该中间体保存断裂的磷酸二酯键的键能以供以后重新连接。拓扑异构酶可分为两类。其中一些酶通过在 DNA 中引入瞬时单链断裂来发挥作用。这类所谓的切口闭合酶的原型是 Wang (1971) 首次在大肠杆菌提取物中检测到的蛋白质。属于这一组的其他酶是真核切口闭合酶（综述，参见 Champoux 1978）和噬菌体的 mt 基因蛋白（Nash 等人，本卷）。相比之下，最近发现的几种拓扑异构酶构成了第二种机制类型，因为它们似乎通过使双螺旋 DNA 片段穿过 DNA 中的瞬时双链断裂来发挥作用。这些酶包括噬菌体 T4 ATP 依赖性拓扑异构酶（Liu 等人，1979、1980）、DNA 旋转酶（Brown 和 Cozzarelli 1979；Mizuuchi 等人，1980a）以及从 HeLa 细胞（L F. Liu，个人）、果蝇胚胎中分离的部分纯化的 ATP 依赖性真核拓扑异构酶。 （刘 等人。 1980）和非洲爪蟾卵母细胞（Baldi 等人，1980）。 一种能够断裂并重新连接 DNA 的酶显然是一种将断链末端从一个 DNA 分子转移到另一个 DNA 分子的功能的候选者，从而为重组机制提供了一个潜在的步骤，正如 Champoux (1977) 所讨论的。事实上，有一些有趣的例子说明了这两种活动之间的密切联系。噬菌体 XI74 的顺反子 A 蛋白在 X174 DNA 的复制形式中产生特异性断裂（Henry 和 Knippers 1974），并且可以将断裂末端转移到新复制链上的同源位置（Eisenberg 等，1977），据报道，它具有拓扑异构酶活性（Ikeda 等，1976），相关的基因-II 蛋白也具有拓扑异构酶活性（Ikeda 等，1976）。 噬菌体 fd（Meyer 和 Geider 1979）。类似地，噬菌体的 int 基因蛋白参与 h 整合重组过程中的链转移，具有拓扑异构酶活性（Kikuchi 和 Nash 1979）。相反，酶首先被研究为拓扑结构
Enzymes that catalyze the transient breakage and rejoining of DNA phosphodiester bonds occur widely in nature. In some cases, they have been initially identified as topoisomerases, so named because they are able to mediate the interconversion of topological isomers of DNA (eg, by removing or introducing superhelical turns). With all topoisomerases, breakage of DNA appears to be coupled to the formation of a covalently linked enzyme-DNA intermediate that conserves the bond energy of the broken phosphodiester bond for later rejoining. Topoisomerases may be grouped into two classes. Some of these enzymes function by introducing a transient single-strand break into DNA. The archetype of this class of so-called nicking-closing enzymes is the~ o protein first detected by Wang (1971) in extracts from Escherichia coli. Other enzymes belonging to this group are the eukaryotic nicking-closing enzymes (for review, see Champoux 1978) and the mt-gene protein of phage~,(Nash et al., this volume). In contrast, several recently discovered topoisomerases constitute a second mechanistic type in that they appear to act by passing a double-helical DNA segment through a transiem double-strand break in DNA. These enzymes include the phage T4 ATP-dependent topoisomerase (Liu et al. 1979, 1980), DNA gyrase (Brown and Cozzarelli 1979; Mizuuchi et al 1980a), and the partially purified ATP-dependent eukaryotic topoisomerases isolated from HeLa cells (L F. Liu, pers. comm.), Drosophila melanogaster embryos (Liu et al. 1980), and Xenopus laevis oocytes (Baldi et al. 1980).An enzyme that breaks and rejoins DNA is an obvious candidate for a function that will transfer a brokenstrand end from one DNA molecule to another, thus supplying one potential step in a recombination mechanism, as discussed by Champoux (1977). Indeed, there are some intriguing examples of the close connection between the two types of activity. The cistron-A protein of phage~ XI74, which produces a specific break in the replicative form of~ X174 DNA (Henry and Knippers 1974) and can transfer the broken end to the homologous position on a newly replicated strand (Eisenberg et al. 1977), has also been reported to have a topoisomerase activity (Ikeda et al. 1976), as has the related gene-II protein of phage fd (Meyer and Geider 1979). Similarly, the int-gene protein of phage~, which participates in strand transfer during h integrative recombination, possesses a topoisomerase activity (Kikuchi and Nash 1979). Conversely, enzymes first studied as topo-