Meng W, Belyaeva T, Savery N J, Busby S J, Ross W E, Gaal T, Gourse R L, Thomas M S
Laboratory of Molecular Microbiology, Division of Genomic Medicine, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX, UK.
Nucleic Acids Res. 2001 Oct 15;29(20):4166-78. doi: 10.1093/nar/29.20.4166.
The UP element stimulates transcription from the rrnB P1 promoter through a direct interaction with the C-terminal domain of the RNA polymerase alpha subunit (alphaCTD). We investigated the effect on transcription from rrnB P1 of varying both the location of the UP element and the length of the alpha subunit interdomain linker, separately and in combination. Displacement of the UP element by a single turn of the DNA helix resulted in a large decrease in transcription from rrnB P1, while displacement by half a turn or two turns totally abolished UP element-dependent transcription. Deletions of six or more amino acids from within the alpha subunit linker resulted in a decrease in UP element-dependent stimulation, which correlated with decreased binding of alphaCTD to the UP element. Increasing the alpha linker length was less deleterious to RNA polymerase function at rrnB P1 but did not compensate for the decrease in activation that resulted from displacing the UP element. Our results suggest that the location of the UP element at rrnB P1 is crucial to its function and that the natural length of the alpha subunit linker is optimal for utilisation of the UP element at this promoter.
上游元件（UP元件）通过与RNA聚合酶α亚基的C端结构域（αCTD）直接相互作用来刺激rrnB P1启动子的转录。我们分别并联合研究了改变UP元件的位置和α亚基结构域间连接区的长度对rrnB P1转录的影响。DNA螺旋单圈移位使UP元件移位，导致rrnB P1转录大幅下降，而半圈或两圈移位则完全消除了UP元件依赖性转录。α亚基连接区内缺失六个或更多氨基酸会导致UP元件依赖性刺激降低，这与αCTD与UP元件的结合减少相关。增加α连接区长度对rrnB P1处的RNA聚合酶功能损害较小，但无法弥补因UP元件移位导致的激活下降。我们的结果表明，rrnB P1处UP元件的位置对其功能至关重要，并且α亚基连接区的天然长度对于该启动子处UP元件的利用是最佳的。
