Escherichia coli type-1 topoisomerases: identification, mechanism, and role in recombination.
Escherichia coli type-1 topoisomerases: identification, mechanism, and role in recombination.
复制标题
大肠杆菌 1 型拓扑异构酶：鉴定、机制和在重组中的作用。
DOI：
10.1101/sqb.1983.047.01.088
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Cozzarelli,NR
中科院分区：
文献类型：
--
作者：
Dean,F;Krasnow,MA;Otter,R;Matzuk,MM;Spengler,SJ;Cozzarelli,NR
拓扑异构酶催化DNA链的协同断裂和重新聚集。断裂的磷酸二酯键的能量在酶与DNA的共价键中是保守的，允许在不存在外部能量源的情况下重新密封断裂。拓扑异构酶仔细地控制断裂和重组过程，在DNA断裂时从不离开DNA。这些酶进行不同的反应，包括超螺旋，连锁，打结，重组和DNA复制的各个方面。2型拓扑异构酶产生短暂的双链断裂并使双链DNA通过断裂。这改变了DNA的拓扑连接数（Lk）在两个步骤中，如符号反转机制所解释的（Brown and Cozzarelli 1979; Liu et al. 1980; Gellert 1981）。另一方面，1型拓扑异构酶一次仅断裂一条链，并以一步一步地改变Lk（Champoux 1978; Wang and Liu 1979; Cozzarelli 1980 b）。在本文中，我们专注于1型拓扑异构酶的大肠杆菌，酶，最近受到越来越多的关注。考虑了五个主题。首先，在分析负超螺旋拓扑异构体的电泳迁移率时，我们发现凝胶上相邻DNA条带的连接数不需要相差一个。其次，我们发现了一个新的E。大肠杆菌拓扑异构酶，拓扑异构酶III。第三，探讨了E.大肠杆菌拓扑异构酶I已被阐明。第四，我们描述了参与1型拓扑异构酶，Tn 3的分解酶，在位点特异性重组。在I型拓扑异构酶的连锁和重组中，双链DNA通过一次一条单链的DNA断裂和重新连接而拓扑重排。第五，我们考虑哪些细胞过程可能特别适合参与的类型-1，但不是类型-2，拓扑异构酶。
Topoisomerases catalyze the concerted breakage and reunion of DNA strands. The energy of the broken phosphodiester bond is conserved in a covalent linkage of the enzyme to DNA, allowing the break to be resealed in the absence of an external energy source. Topoisomerases carefully control the breakage and reunion process, never leaving the DNA while it is broken. These enzymes carry out diverse reactions including supercoiling, catenation, knotting, recombination, and aspects of DNA replication. Type-2 topoisomerases make a transient double-stranded break and pass duplex DNA through the break. This changes the topological linking number of DNA (Lk) in steps of two, as explained by the sign-inversion mechanism (Brown and Cozzarelli 1979; Liu et al. 1980; Gellert 1981). Type-1 topoisomerases, on the other hand, break only one strand at a time and alter the Lk in steps of one (Champoux 1978; Wang and Liu 1979; Cozzarelli 1980b). In this paper we focus on the type-1 topoisomerases of Escherichia coli, enzymes that have recently received increased attention. Five topics are considered. First, in the analysis of the electrophoretic mobility of negatively supercoiled topoisomers, we discovered that adjacent DNA bands on a gel need not differ by one in linking number. Second, we identified a new E. coli topoisomerase, topoisomerase III. Third, the mechanism of catenation of duplex DNA rings by E. coli topoisomerase I has been elucidated. Fourth, we describe the involvement of a type-1 topoisomerase, the resolvase of Tn3, in site-specific recombination. In catenation and recombination by type-I topoisomerases, duplex DNA is topologically rearranged via the breakage and rejoining of DNA a single strand at a time. Fifth, we consider what cellular processes might be particularly suited for the involvement of type-l, but not type-2, topoisomerases.