Mutational Analysis of E coli DNA Topoisomerase III

描述(申请人提供)：DNA拓扑异构酶是一种可以改变 DNA的连接数，并因此负责拓扑之间的相互作用 以及DNA分子内的内部转化。这些转换包括 DNA的打结或解结，DNA的超级卷曲或松弛 分子内转化)和DNA的链化(或去链) 分子间转化)。拓扑异构酶可分为两大类 类别，类型I和类型II。类型I酶可以进一步细分 转化为IA型原核生物DNA拓扑异构酶I(Topo I)和III(Topo III)，以及 真核DNA拓扑异构酶III(Topo III)和IB型(真核DNA 拓扑异构酶I和噬菌体重组酶)。事实证明，Topo 类似III的活动似乎在两者的同源通路中起作用 原核生物和真核生物。特别是，这一点正变得越来越明显 TOPO III类酶与DNA解旋酶相互作用并作用于 抑制酵母和大肠杆菌中的重组。大肠埃希氏菌TOPO III是 对生化和基因特征都非常敏感；因此， 大肠杆菌Topo III的特性对于建立 这些酶在原核生物DNA代谢中的作用 真核生物。这笔赠款的具体目的是： 1.进一步鉴定大肠杆菌Topo III介导的催化作用中的残基 并阐明了IA型拓扑异构酶介导的催化机制 2.阐明大肠杆菌Topo III在重组中的作用 3.确定并研究拓扑异构酶III与其他 细胞蛋白质，特别是DNA解旋酶。

DESCRIPTION (Provided by applicant): DNA topoisomerases are enzymes that alter the linking number of DNA and, as such, are responsible for topological inter- and intra-conversions within DNA molecules. These conversions include the knotting or unknotting of DNA, the supercoiling or relaxation of DNA (an intra-molecular conversion) and the catenation (or decatenation) of DNA (an inter-molecular conversion). Topoisomerases can be classified into two major categories, type I and type II. The type I enzymes can be further subdivided into type IA prokaryotic DNA topoisomerase I (Topo I) and III (Topo III), and eukaryotic DNA topoisomerase III (Topo III)) and type IB (eukaryotic DNA topoisomerase I and bacteriophage recombinases). It has been shown that Topo III-like activities appear to function in homologous pathways in both prokaryotes and eukaryotes. In particular, it is becoming increasingly evident that Topo III-like enzymes interact with DNA helicases and act in the suppression of recombination in both yeast and E. coli. Topo III of E. coli is extremely amenable to both biochemical and genetic characterization; therefore, the characterization of E. coli Topo III has been very useful to establishing the role of these enzymes in the DNA metabolism of both prokaryotes and eukaryotes. The specific aims of this grant are: 1. Further identify residues involved in E. coli Topo III-mediated catalysis and elucidate the mechanism of type IA topoisomerase-mediated catalysis 2. Elucidate the role of E. coli Topo III in recombination 3. Identify and examine the role of topoisomerase III interactions with other cellular proteins, in particular, DNA helicases.