THE ARTHROPOD INITIATOR - THE CAPSITE CONSENSUS PLAYS AN IMPORTANT ROLE IN TRANSCRIPTION
THE ARTHROPOD INITIATOR - THE CAPSITE CONSENSUS PLAYS AN IMPORTANT ROLE IN TRANSCRIPTION
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DOI：
10.1016/0965-1748(93)90085-7
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发表时间：
1993-01-01
影响因子：
3.8
通讯作者：
CHERBAS, P
中科院分区：
文献类型：
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作者：
CHERBAS, L;CHERBAS, P
大约 25% 的节肢动物 RNA 聚合酶 II 转录启动子包含一个或多个从 (-10, +10) 区间开始的 TCAGT 序列拷贝。该序列及其同源 ACAGT、GCAGT 和 TCATT 在统计上的明显过度表达表明它们可能是重要的启动子元件。它们与 TdT 类脊椎动物起始子 (Inrs) 的集体序列相似性表明脊椎动物和节肢动物元件是同源的。先前在脊椎动物系统中的研究强调了 Inr 在缺乏 TATA 盒的启动子中的作用，它可以作为聚合酶 II 起始的替代暂存位点。然而，很明显，Inr 序列绝不限于 TATA 缺陷的启动子。使用含有 TATA 的果蝇基因 Eip28/29 进行的功能测试支持这样的观点：Inr 是兼性启动子元件，在某些条件下是有效转录所必需的。例如，Inr 保护 Eip28/29 的基础表达免受蜕皮激素反应元件的沉默作用。此外，Inr 是 Eip28/29 基础活性增强子功能所必需的。我们得出结论，Inrs 是在高等真核生物中零星发现的启动子元件，对 Inr 的需求取决于可能存在于给定基因中的其他启动子元件的阵列，并且 Inrs 可能允许增强子区分启动子。
Approximately 25% of arthropod RNA polymerase II-transcribed promoters contain one or more copies of the sequence TCAGT beginning within the interval (-10, +10). The clear statistical overrepresentation of this sequence and, to a lesser extent, of its cognates ACAGT, GCAGT, and TCATT, implies that they may be significant promoter elements. Their collective sequence similarity to vertebrate initiators (Inrs) of the TdT class suggests that the vertebrate and arthropod elements are homologous. Prior work in vertebrate systems has emphasized the role of the Inr in promoters lacking TATA boxes, where it can serve as an alternate staging site for polymerase II initiation. However, it is clear that the Inr sequence is by no means restricted to TATA-deficient promoters. Functional tests using the TATA-containing Drosophila gene Eip28/29 support the idea that the Inr is a facultative promoter element, required for efficient transcription under some conditions. For example, the Inr protects basal expression of Eip28/29 from the silencing effect of ecdysone response elements. In addition, the Inr is required for the function of an enhancer of basal activity in Eip28/29. We conclude that Inrs are promoter elements found sporadically throughout the higher eukaryotes, that the requirement for an Inr depends upon the array of other promoter elements which may be present in a given gene, and that Inrs may permit enhancers to discriminate among promoters.