Regulation of Escherichia coli topA gene transcription: involvement of a sigmaS-dependent promoter.
Regulation of Escherichia coli topA gene transcription: involvement of a sigmaS-dependent promoter.
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大肠杆菌 topA 基因转录的调控：sigmaS 依赖性启动子的参与。
DOI：
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发表时间：
1997
影响因子：
5.6
通讯作者：
Y. Tse‐Dinh
中科院分区：
文献类型：
--
作者：
H. Qi;R. Menzel;Y. Tse‐Dinh
为了研究大肠杆菌topA基因的转录调控，采用引物延伸法确定了染色体topA基因的转录起始位点。当细胞在LB培养基中生长到对数生长期时，可以鉴定出四个转录起始位点。这些位点中的三个对应于先前使用topA-galK融合质粒表征的启动子P1、P2和P4。在所采用的条件下，在染色体topA基因上不使用在质粒上有活性的P3启动子。有一个新的转录起始位点对应于一个新的启动子Px 1。当细胞开始进入稳定期时，启动子Px 1逐渐成为topA的主要转录起始位点，而启动子P2和P4的转录减少。在大肠coli突变体缺乏sigmaS（rpoS基因产物），稳定期特异性sigma因子，从启动子Px 1的转录诱导被消除。在另一个缺乏H-NS活性的突变体中，导致对数期sigmaS水平增加，对数期期间启动子Px 1的转录增加。因此，Px 1似乎受到sigmaS的调节。在热休克期间，染色体上的启动子P1的活性增加，这与先前使用topA-galK融合质粒获得的结果一致，表明P1是σ 32依赖性热休克启动子。启动子P2和P4最有可能被sigma 70识别。在rpoS突变体中拓扑异构酶I蛋白的总水平在稳定期没有显著降低，这是由于其他topA启动子的转录起始增加。利用多个sigma因子启动topA的转录可能对E.改变生长条件。
To investigate the regulation of Escherichia coli topA gene transcription, primer extension was employed to determine the transcription initiation sites from the chromosomal topA gene. When cells were grown in LB medium to log phase, four transcription initiation sites could be identified. Three of these sites corresponded to promoters P1, P2 and P4 previously characterized using topA-galK fusion plasmids. The P3 promoter that is active on the plasmid was not utilized at the chromosomal topA gene under the conditions employed. There was a new transcription initiation site corresponding to a new promoter Px1. When cells started to enter stationary phase, promoter Px1 gradually became the major transcription initiation site for topA, while transcription from promoters P2 and P4 decreased. In an E. coli mutant lacking sigmaS (the rpoS gene product), the stationary phase specific sigma factor, the induction of transcription from promoter Px1 was abolished. In another mutant lacking H-NS activity, resulting in increased sigmaS level in log-phase, the transcription from promoter Px1 during log phase was increased. Thus Px1 appeared to be regulated by sigmaS. The activity of promoter P1 on the chromosome increased during heat shock, consistent with the previous result obtained using the topA-galK fusion plasmid showing that P1 is a sigma32-dependent heat shock promoter. Promoters P2 and P4 were most likely to be recognized by sigma70. The total level of topoisomerase I protein in the rpoS mutant was not reduced significantly in stationary phase due to increased transcription initiation from the other topA promoters. The utilization of multiple sigma factors for transcription initiation of topA could be important for adaptation of E. coli to change in growth conditions.
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影响因子：
56.9
作者：
Elaine A. Ostrander;P. Benedetti;JC Wang
通讯作者：
Elaine A. Ostrander;P. Benedetti;JC Wang
拓扑异构酶 III（而非拓扑异构酶 I）可以支持 θ 型 DNA 复制过程中新生链的伸长。
DOI：
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发表时间：
1994
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Hiasa,H;Marians,KJ
通讯作者：
Marians,KJ
DOI：
10.1016/s0021-9258(17)42136-3
发表时间：
1994-01
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
M. Drolet;M. Drolet;X. Bi;Leroy F. Liu
通讯作者：
M. Drolet;M. Drolet;X. Bi;Leroy F. Liu
编码大肠杆菌 DNA 拓扑异构酶 I 的 topA 基因的完整核苷酸序列。
影响因子：
5.6
作者：
Tse-Dinh,YC;Wang,JC
通讯作者：
Wang,JC