Lee J S, Galvin K M, Shi Y
Committee on Virology, Harvard Medical School, Boston, MA 02115.
Proc Natl Acad Sci U S A. 1993 Jul 1;90(13):6145-9. doi: 10.1073/pnas.90.13.6145.
Two promoter elements are important for basal-level transcription, the TATA motif typically located 30 nucleotides upstream of the transcription initiation site and the initiator (Inr) element encompassing the start site. The mechanism of how Inr elements work is poorly understood, partly because very few proteins that bind to Inr elements have been identified and isolated. The recently cloned YY1 is such an Inr-binding protein. YY1 is able to direct transcription upon binding to its recognition sequence in vitro. The ability of YY1 to initiate transcription is augmented by the presence of a TATA motif or binding sites for transcription factor Sp1. To study the mechanism underlying the apparent functional cooperation between YY1 and Sp1, we explored the possibility of protein-protein interactions between these two transcription factors. We found that YY1 and Sp1 can form a physical complex. In addition, we identified domains within YY1 and Sp1 that mediate their interactions with each other. The physical interaction between YY1 and Sp1 may thus form the basis for the functional interplay observed previously.
两种启动子元件对基础水平转录很重要，即通常位于转录起始位点上游30个核苷酸处的TATA基序和包含起始位点的起始子（Inr）元件。Inr元件的作用机制尚不清楚，部分原因是很少有与Inr元件结合的蛋白质被鉴定和分离出来。最近克隆的YY1就是这样一种与Inr结合的蛋白质。YY1在体外与其识别序列结合后能够指导转录。TATA基序或转录因子Sp1的结合位点的存在增强了YY1启动转录的能力。为了研究YY1和Sp1之间明显的功能协同作用的潜在机制，我们探讨了这两种转录因子之间蛋白质-蛋白质相互作用的可能性。我们发现YY1和Sp1可以形成物理复合物。此外，我们确定了YY1和Sp1中介导它们相互作用的结构域。因此，YY1和Sp1之间的物理相互作用可能构成了先前观察到的功能相互作用的基础。
