Type I topoisomerase activity is required for proper chromosomal segregation in Escherichia coli.
Type I topoisomerase activity is required for proper chromosomal segregation in Escherichia coli.
复制标题
I 型拓扑异构酶活性是大肠杆菌中正确染色体分离所必需的。
DOI：
10.1073/pnas.171579898
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发表时间：
2001
影响因子：
11.1
通讯作者：
DiGate,RJ
中科院分区：
文献类型：
--
作者：
Zhu,Q;Pongpech,P;DiGate,RJ
I型DNA拓扑异构酶是DNA代谢中普遍存在的酶，具有两种I型拓扑异构酶活性，即DNA拓扑异构酶I(Topo I)和拓扑异构酶III(Topo III)。编码Topo III(TopB)的基因可以在不影响细胞活力的情况下被删除。具有Topo I(TopA)编码基因缺失的细胞只有在存在额外的代偿性突变时才能存活。在存在补偿突变的情况下，Topo I缺失菌株正常生长；然而，如果Topo III活性在这些细胞中受到抑制，它们会广泛地形成丝状结构，并具有异常的类核结构。这些缺陷可以通过缺失ecA基因来抑制，这表明这些酶可能参与了RecA介导的重组，并可能在分割前特异性地分解重组中间产物。
Type I DNA topoisomerases are ubiquitous enzymes involved in many aspects of DNA metabolism.Escherichia colipossesses two type I topoisomerase activities, DNA topoisomerase I (Topo I) and III (Topo III). The gene encoding Topo III (topB) can be deleted without affecting cell viability. Cells possessing a deletion of the gene encoding Topo I (topA) are only viable in the presence of an additional compensatory mutation. In the presence of compensatory mutations, Topo I deletion strains grow normally; however, if Topo III activity is repressed in these cells, they filament extensively and possess an abnormal nucleoid structure. These defects can be suppressed by the deletion of therecAgene, suggesting that these enzymes may be involved in RecA-mediated recombination and may specifically resolve recombination intermediates before partitioning.