Narayan S, Wilson S H
Sealy Center for Molecular Science, University of Texas Medical Branch, Galveston 77555, USA.
Oncogene. 2000 Sep 28;19(41):4729-35. doi: 10.1038/sj.onc.1203823.
In the present studies, we have examined the effect of Sp1 on the activation of the human DNA polymerase beta (beta-pol), a TATA-less promoter. A HeLa cell nuclear extract (NE) based in vitro runoff transcription system of core beta-pol promoter human DNA (pbetaP8) three-step kinetic model of transcription initiation were used to describe the kinetic effect of Sp1. The results showed that distal Sp1-binding sites in the core beta-pol promoter are important for transcriptional activation of the pbetaP8 promoter. A detailed kinetic analysis showed that Sp1 stimulates the activity of the pbetaP8 promoter through distal Sp1-binding sites by increasing the amount of recruitment, instead of stimulating the apparent rate of RPc assembly (k1). There was no significant effect of Sp1 on the apparent rate of open complex (RPo) formation (k2) or on the apparent rate of promoter clearance (k3) of the pbetaP8 promoter. These studies define the kinetic mechanisms by which Sp1 may regulate the rate of transcript formation of the pbetaP8 promoter, and these results may have implications for Sp1 regulation of TATA-less promoters.
在本研究中，我们检测了Sp1对人DNA聚合酶β（β-pol）启动子（一个无TATA盒的启动子）激活的影响。基于HeLa细胞核提取物（NE）的核心β-pol启动子人DNA（pbetaP8）体外径流转录系统及转录起始的三步动力学模型，用于描述Sp1的动力学效应。结果表明，核心β-pol启动子中的远端Sp1结合位点对pbetaP8启动子的转录激活很重要。详细的动力学分析表明，Sp1通过增加募集量，而非刺激RPc组装的表观速率（k1），经远端Sp1结合位点刺激pbetaP8启动子的活性。Sp1对pbetaP8启动子开放复合物（RPo）形成的表观速率（k2）或启动子清除的表观速率（k3）无显著影响。这些研究确定了Sp1调控pbetaP8启动子转录形成速率的动力学机制，这些结果可能对Sp1调控无TATA盒启动子具有重要意义。
