POSITION AND DENSITY EFFECTS ON REPRESSION BY STATIONARY AND MOBILE DNA-BINDING PROTEINS
POSITION AND DENSITY EFFECTS ON REPRESSION BY STATIONARY AND MOBILE DNA-BINDING PROTEINS
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DOI：
10.1101/gad.3.2.185
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发表时间：
1989-02-01
影响因子：
10.5
通讯作者：
DAVIS, RW
中科院分区：
文献类型：
--
作者：
ELLEDGE, SJ;DAVIS, RW
我们研究了两种类型的DNA结合蛋白对细菌阻遏的影响。首先，在体内研究了操纵子定位对固定DNA结合蛋白（Lac阻遏物和Trp阻遏物）阻遏的影响。操纵子数量和定位在确定体内抑制水平中起作用。位于启动子内的操纵子比位于转录起始处的操纵子是更有效的调节子。其次，我们研究了DNA结合蛋白密度对阻遏的影响，使用移动的DNA结合蛋白，大肠杆菌RNA聚合酶。我们采用了一种转录干扰试验，使用收敛的转录单位。观察到强合成启动子conI及其衍生物干扰aadA基因的表达，这赋予其宿主壮观霉素抗性。RNA聚合酶的转录干扰只发生在顺式，并有很强的依赖于聚合酶的密度，通过不同的启动子强度调制。大约四倍的密度变化完全消除了观察到的转录干扰。几个模型进行了讨论，以解释观察到的静止和移动的DNA结合蛋白的阻遏模式。
We have investigated the effects of two types of DNA-binding proteins on bacterial repression. First, the effects of operator positioning on repression by stationary DNA-binding proteins, the Lac repressor and the Trp repressor, were examined in vivo. Both operator number and positioning play a role in determining in vivo levels of repression. Operators located within a promoter are more efficient regulators than those positioned at the start of transcription. Second, we investigated the effects of DNA-binding protein density on repression using an mobile DNA-binding protein, Escherichia coli RNA polymerase. We employed a transcriptional interference assay using convergent transcriptional units. The strong synthetic promoter conI and its derivatives were observed to interfere with expression of the aadA gene, which confers spectinomycin resistance upon its host. Transcriptional interference by RNA polymerase occurred only in cis and had a strong dependence on polymerase density that was modulated by varying the promoter strengths. A change in the density of approximately fourfold completely abolished the observed transcriptional interference. Several models are discussed to explain the repression patterns observed for stationary and mobile DNA-binding proteins.