ROLE OF INTEGRATION HOST FACTOR IN THE REGULATION OF THE GLNHP2 PROMOTER OF ESCHERICHIA-COLI
ROLE OF INTEGRATION HOST FACTOR IN THE REGULATION OF THE GLNHP2 PROMOTER OF ESCHERICHIA-COLI
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DOI：
10.1073/pnas.88.5.1631
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发表时间：
1991-03-01
影响因子：
11.1
通讯作者：
MAGASANIK, B
中科院分区：
文献类型：
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作者：
CLAVERIEMARTIN, F;MAGASANIK, B
大肠杆菌的glnHPQ操纵子编码高亲和力谷氨酰胺转运系统的组成部分。该操纵子的两个启动子之一glnHp2负责操纵子在氮限制条件下的表达。通用氮调节蛋白(NR(I))与转录起始点-109和-122处的两个重叠位点结合，当被磷酸化时，通过催化封闭的sigma-54-RNA聚合酶启动子复合体异构化为开放复合体来激活glnHp2的转录。DNA-弯曲蛋白整合宿主因子(IHF)结合在glnHp2上游的一个位点上，并增强NR(I)磷酸形成开放复合体的活性。NR(I)结合位点可以进一步向上游移动数百个碱基对，而不会改变NR(I)磷酸激活开放络合物形成的能力。然而，在这种情况下，IHF减少了开放的络合物形成。我们认为，IHF诱导的弯曲可以促进或阻碍NR(I)磷酸与封闭的复合体之间的相互作用，这取决于NR(I)磷酸和Sigma-54-RNA聚合酶在DNA上的相对位置。
The glnHPQ operon of Escherichia coli encodes components of the high-affinity glutamine transport system. One of the two promoters of this operon, glnHp2, is responsible for expression of the operon under nitrogen-limiting conditions. The general nitrogen regulatory protein (NR(I)) binds to two overlapping sites centered at -109 and -122 from the transcription start site and, when phosphorylated, activates transcription of glnHp2 by catalyzing isomerization of the closed sigma-54-RNA polymerase promoter complex to an open complex. The DNA-bending protein integration host factor (IHF) binds to a site immediately upstream of glnHp2 and enhances the activation of open complex formation by NR(I) phosphate. The NR(I)-binding sites can be moved several hundred base pairs further upstream without altering the ability of NR(I) phosphate to activate open complex formation. However, in this case, IHF diminishes open complex formation. We propose that the IHF-induced bend can facilitate or obstruct the interaction between NR(I) phosphate and the closed complex depending on the relative positions of NR(I) phosphate and sigma-54-RNA polymerase on the DNA.