Topoisomerase III can serve as the cellular decatenase in Escherichia coli
Topoisomerase III can serve as the cellular decatenase in Escherichia coli
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DOI：
10.1074/jbc.m211211200
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发表时间：
2003-03-07
影响因子：
4.8
通讯作者：
Marians, KJ
中科院分区：
文献类型：
--
作者：
Nurse, P;Levine, C;Marians, KJ
topB，编码拓扑异构酶III，被确定为温度敏感的parC1215等位基因的高拷贝抑制基因，编码拓扑异构酶IV的亚基之一。拓扑异构酶III在非允许的温度下过表达，随后恢复及时染色体decatenation和抑制致死性的菌株携带温度敏感的帕雷或parC等位基因。通过开发一种用于前环烷烃解链的体外测定法，我们直接证明了拓扑异构酶III和拓扑异构酶IV在该任务中是有效的，而DNA促旋酶在前环烷烃去除中是非常低效的。这些观察结果表明，前链烷解链足以维持细胞中复制子染色体的解链。
topB, encoding topoisomerase III, was identified as a high copy suppressor of the temperature-sensitive parC1215 allele, encoding one of the subunits of topoisomerase IV. Overexpression of topoisomerase III at the nonpermissive temperature was shown subsequently to restore timely chromosome decatenation and suppress lethality in strains carrying either temperature-sensitive parE or parC alleles. By developing an assay in vitro for precatenane unlinking, we demonstrated directly that both topoisomerase III and topoisomerase IV were efficient at this task, whereas DNA gyrase was very inefficient at precatenane removal. These observations suggest that precatenane unlinking is sufficient to sustain decatenation of replicating daughter chromosomes in the cell.