RecA can stimulate the relaxation activity of topoisomerase I:: Molecular basis of topoisomerase-mediated genome-wide transcriptional responses in Escherichia coli
RecA can stimulate the relaxation activity of topoisomerase I:: Molecular basis of topoisomerase-mediated genome-wide transcriptional responses in Escherichia coli
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RecA 可刺激拓扑异构酶 I 的弛豫活性：大肠杆菌中拓扑异构酶介导的全基因组转录反应的分子基础
DOI：
10.1093/nar/gkl981
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发表时间：
2007-01-01
影响因子：
14.9
通讯作者：
Hiasa, Hiroshi
中科院分区：
文献类型：
--
作者：
Reckinger, Amy R.;Jeong, Kyeong Soo;Hiasa, Hiroshi
由DNA拓扑异构酶控制的染色体的超螺旋性调节全局基因表达。对调节促旋酶功能的转录应答的研究已经确定了两种类型的拓扑异构酶介导的转录应答：（i）由促旋酶中的突变引起的稳态变化，如GyrA中的D82G突变，和（ii）由促旋酶的抑制引起的动态变化。我们推测，稳态效应是由于促旋酶的生化特性的变化，而动态效应是由于超螺旋和松弛活动之间的不平衡，这似乎是由RecA活动的影响。在此，我们提出了假设的机制的生化证据。GyrA D82G促旋酶表现出降低的超螺旋活性。RecA蛋白可以通过干扰DNA促旋酶的活性或促进松弛反应来影响超螺旋和松弛活性之间的平衡。RecA对促旋酶的超螺旋活性没有影响，但对拓扑异构酶I的松弛活性有刺激作用。这种刺激是特异性的，需要形成活性RecA细丝。这些结果表明，RecA和拓扑异构酶I之间的功能相互作用是负责RecA介导的松弛依赖的大肠杆菌染色体的转录活性的调制。
The superhelicity of the chromosome, which is controlled by DNA topoisomerases, modulates global gene expression. Investigations of transcriptional responses to the modulation of gyrase function have identified two types of topoisomerase-mediated transcriptional responses: (i) steady-state changes elicited by a mutation in gyrase, such as the D82G mutation in GyrA, and (ii) dynamic changes elicited by the inhibition of gyrase. We hypothesize that the steady-state effects are due to the changes in biochemical properties of gyrase, whereas the dynamic effects are due to an imbalance between supercoiling and relaxation activities, which appears to be influenced by the RecA activity. Herein, we present biochemical evidence for hypothesized mechanisms. GyrA D82G gyrase exhibits a reduced supercoiling activity. The RecA protein can influence the balance between supercoiling and relaxation activities either by interfering with the activity of DNA gyrase or by facilitating the relaxation reaction. RecA has no effect on the supercoiling activity of gyrase but stimulates the relaxation activity of topoisomerase I. This stimulation is specific and requires formation of an active RecA filament. These results suggest that the functional interaction between RecA and topoisomerase I is responsible for RecA-mediated modulation of the relaxation-dependent transcriptional activity of the Escherichia coli chromosome.