Governor of the glnAp2 promoter of Escherichia coli
Governor of the glnAp2 promoter of Escherichia coli
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DOI：
10.1046/j.1365-2958.2002.03211.x
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发表时间：
2002-12-01
影响因子：
3.6
通讯作者：
Ninfa, AJ
中科院分区：
文献类型：
--
作者：
Atkinson, MR;Pattaramanon, N;Ninfa, AJ
激活剂NRIsimilar to P（NtrCsimilar to P）的低亲和力位点，增强子和glnAp2启动子之间的映射负责限制启动子活性在高浓度的NRIsimilar to P在完整的细胞和在体外转录系统组成的纯化的细菌成分。也就是说，低亲和力位点构成"总督"，限制最大启动子活性。由于调控位点本身远离启动子，它们显然通过阻止使增强子结合的激活剂和启动子结合的聚合酶接近的激活DNA环的形成或通过阻止增强子结合的激活剂和聚合酶之间的有效相互作用来起作用。glnAp2启动子上有效的增强子和调控子位点的组合在激活剂浓度低时提供了启动子的有效激活，而在激活剂浓度高时限制了启动子活性的最大水平。
Low-affinity sites for the activator NRIsimilar toP (NtrCsimilar toP) that map between the enhancer and the glnAp2 promoter were responsible for limiting promoter activity at high concentrations of NRIsimilar toP in intact cells and in an in vitro transcription system consisting of purified bacterial components. That is, the low-affinity sites constitute a 'governor', limiting the maximum promoter activity. As the governor sites are themselves far from the promoter, they apparently act either by preventing the formation of the activation DNA loop that brings the enhancer-bound activator and the promoter-bound polymerase into proximity or by preventing a productive interaction between the enhancer-bound activator and polymerase. The combination of potent enhancer and governor sites at the glnAp2 promoter provides for efficient activation of the promoter when the activator concentration is low, while limiting the maximum level of promoter activity when the activator concentration is high.