Mutational Analysis of E coli DNA Topoisomerase III

描述（由申请人提供）：DNA拓扑异构酶是改变 DNA的连接数，因此，负责拓扑间- 和DNA分子内的内部转换。这些转换包括 DNA的打结或解结，DNA的超螺旋或松弛（ 分子内转换）和DNA的连锁（或解链）（ 分子间转化）。拓扑异构酶可分为两大类 第一类和第二类。I型酶可以进一步细分 IA型原核DNA拓扑异构酶I（Topo I）和III（Topo III），和 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）。研究表明，Topo III样活性似乎在两种细胞的同源途径中起作用。 原核生物和真核生物。尤其是， 类似Topo III的酶与DNA解旋酶相互作用， 在酵母和E.杆菌Topo III of E.杆菌 非常适合生物化学和遗传表征;因此， 对E. coli Topo III对于建立 这些酶在原核生物和 真核生物这项赠款的具体目标是： 1.进一步鉴定E. coli Topo III介导的催化作用 阐明IA型拓扑异构酶介导的催化机理 2.阐明了E. coli Topo III重组 3.确定并检查拓扑异构酶III与其他蛋白相互作用的作用 细胞蛋白，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.