DIFFERENT ACTIVATION DOMAINS OF SP1 GOVERN FORMATION OF MULTIMERS AND MEDIATE TRANSCRIPTIONAL SYNERGISM
DIFFERENT ACTIVATION DOMAINS OF SP1 GOVERN FORMATION OF MULTIMERS AND MEDIATE TRANSCRIPTIONAL SYNERGISM
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DOI：
10.1101/gad.5.9.1646
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发表时间：
1991-09-01
影响因子：
10.5
通讯作者：
TJIAN, R
中科院分区：
文献类型：
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作者：
PASCAL, E;TJIAN, R
真核生物中通过位点特异性DNA结合蛋白激活转录的过程是基因调控的关键步骤。在这里，我们已经研究了四个不同的激活域的人类转录因子Sp1的属性。在体内瞬时共转染与Sp1的测定表明，模板轴承多个Sp1位点激活转录具有高度的协同作用。然而，没有证据表明Sp1与相邻位点的合作结合。使用Sp1的缺失突变体，我们已经确定富含谷氨酰胺的激活结构域A和B以及先前未表征的羧基末端结构域D都是Sp1协同激活转录所需的。凝胶位移，DNA酶足迹，和化学交联实验揭示了一个很强的相关性之间的能力Sp1突变体形成homomultimeric复合物和它们的能力，协同激活转录时，绑定到多个网站。我们还研究了超激活过程，其中通过锌指与DNA连接的Sp1分子可以通过直接与无指Sp1分子相互作用来增强转录。参与超激活的结构域似乎是实现协同激活所必需的结构域的子集。这些研究结果表明，Sp1的不同结构域进行不同的功能，多聚体复合物的形成可能会直接协同作用和超激活。
The process of transcriptional activation in eukaryotes by site-specific DNA-binding proteins is a key step in gene regulation. Here we have examined the properties of four distinct activator domains of the human transcription factor Sp1. In vivo transient cotransfection assays with Sp1 show that templates bearing multiple Sp1 sites activate transcription with a high degree of synergism. However, there is no evidence of cooperative binding of Sp1 to adjacent sites. Using deletion mutants of Sp1 we have determined that the glutamine-rich activation domains A and B and the previously uncharacterized carboxy-terminal domain D are all required for Sp1 to activate transcription synergistically. Gel-shift, DNase footprinting, and chemical cross-linking experiments reveal a strong correlation between the ability of Sp1 mutants to form homomultimeric complexes and their ability to activate transcription synergistically when bound to multiple sites. We have also examined the process of superactivation, in which a molecule of Sp1 tethered to DNA via its zinc fingers can be transcriptionally enhanced by interacting directly with fingerless Sp1 molecules. The domains involved in superactivation appear to be a subset of those necessary to achieve synergistic activation. These findings suggest that different domains of Sp1 carry out distinct functions and that the formation of multimeric complexes may direct synergism and superactivation.