FACTOR-INDEPENDENT ACTIVATION OF RRNB P1 - AN EXTENDED PROMOTER WITH AN UPSTREAM ELEMENT THAT DRAMATICALLY INCREASES PROMOTER STRENGTH
FACTOR-INDEPENDENT ACTIVATION OF RRNB P1 - AN EXTENDED PROMOTER WITH AN UPSTREAM ELEMENT THAT DRAMATICALLY INCREASES PROMOTER STRENGTH
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DOI：
10.1006/jmbi.1994.1098
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发表时间：
1994-02-04
影响因子：
5.6
通讯作者：
GOURSE, RL
中科院分区：
文献类型：
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作者：
RAO, L;ROSS, W;GOURSE, RL
大肠杆菌RNA启动子rBP 1的非凡强度主要来自核心（-10，-35）区上游序列。我们发现，-40和-60之间的序列增加该启动子的活性至少30倍，在体外和体内。该区域，我们称之为上游（UP）元件，位于-35共有六聚体和先前表征的rRNA转录因子Fis的结合位点之间。UP元件的作用在体内不依赖于Fisin，在体外不依赖于除RNA聚合酶（RNAP）以外的任何其他蛋白。UP元素增加了RNAP与启动子缔合的总体二级速率常数（ka），并且可能增加了表观总体一级异构化常数（ki）。结合先前报道的足迹实验中RNAP对UP元件区域的保护，这些结果表明rrnBP 1具有“扩展”启动子结构，由UP元件和核心启动子区域组成。我们发现UP元件是一个可分离的启动子模块，它可以在rrnBP 1-lachybrid启动子构建体中起增加thelaccore启动子活性的作用。功能性UP元件对于Fis蛋白刺激rrnBP 1不是绝对必要的。
The extraordinary strength of theEscherichia colirRNA promoterrrnBP1 derives primarily from sequences upstream of the core (-10, -35) region. We find that sequences between -40 and -60 increase the activity of this promoter at least 30-foldin vitroandin vivo. This region, which we refer to as the upstream (UP) element, is located between the -35 consensus hexamer and the previously characterized binding sites for the rRNA transcription factor Fis. The effect of the UP element is independent of Fisin vivo, and independent of any other proteins besides RNA polymerase (RNAP)in vitro. The UP element increases the overall second-order rate constant for association of RNAP with the promoter (ka) and probably the apparent overall first-order isomerization constant (ki). Together with the previously reported protection of the UP element region by RNAP in footprinting experiments, these results indicate thatrrnBP1 has an "extended" promoter structure, consisting of the UP element and the core promoter region. We find that the UP element is a separable promoter module that can function to increase the activity of thelaccore promoter in anrrnBP1-lachybrid promoter construct. A functional UP element is not absolutely essential for stimulation ofrrnBP1 by the Fis protein.