SYNERGISTIC ACTIVATION OF TRANSCRIPTION BY ESCHERICHIA-COLI CAMP RECEPTOR PROTEIN
SYNERGISTIC ACTIVATION OF TRANSCRIPTION BY ESCHERICHIA-COLI CAMP RECEPTOR PROTEIN
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DOI：
10.1073/pnas.90.7.3083
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发表时间：
1993-04-01
影响因子：
11.1
通讯作者：
HOCHSCHILD, A
中科院分区：
文献类型：
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作者：
JOUNG, JK;LE, LU;HOCHSCHILD, A
真核生物中基因表达的激活通常涉及多个转录因子的作用，这些转录因子在与特定靶基因结合时协同发挥作用。这种效应的发生是因为多种激活剂可以同时与基础转录机制的一种或多种组分相互作用。在原核生物中，对转录的协同效应的例子要有限得多，通常可以用协同DNA结合来解释。在这里，我们表明，大肠杆菌cAMP受体蛋白（CRP）的功能协同激活转录从衍生物的乳糖启动子，承担第二CRP结合位点上游的天然结合位点。我们目前的证据表明，合作DNA结合的两个CRP二聚体并不占所观察到的合作激活的幅度。相反，我们建议，这两个二聚体刺激转录直接接触RNA聚合酶的两个不同的表面同时进行。因此，CRP的协同激活可能提供了一个相对简单的模型，用于检查高等生物体中这种效应的分子基础。
Activation of gene expression in eukaryotes generally involves the action of multiple transcription factors that function synergistically when bound near a particular target gene. Such effects have been suggested to occur because multiple activators can interact simultaneously with one or more components of the basal transcription machinery. In prokaryotes, examples of synergistic effects on transcription are much more limited and can often be explained by cooperative DNA binding. Here we show that the Escherichia coli cAMP receptor protein (CRP) functions synergistically to activate transcription from a derivative of the lac promoter that bears a second CRP-binding site upstream of the natural binding site. We present evidence indicating that cooperative DNA binding of two CRP dimers does not account for the magnitude of the observed cooperative activation. We suggest, instead, that the two dimers stimulate transcription directly by contacting two distinct surfaces of RNA polymerase simultaneously. Thus, synergistic activation by CRP may provide a relatively simple model for examining the molecular basis of such effects in higher organisms.