Kristie T M, Sharp P A
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
Genes Dev. 1990 Dec;4(12B):2383-96. doi: 10.1101/gad.4.12b.2383.
Trans-activation by the herpes simplex virus (HSV) protein, alpha TIF (VP16), is dependent on an inducible enhancer sequence that contains a homolog of the octamer element. An ordered series of multiprotein complexes can be assembled on this enhancer, requiring the interactions of Oct-1, alpha TIF, and two additional cellular factors (C1 and C2). Oct-1 binds to the octamer homolog, whereas alpha TIF, also a sequence-specific DNA-binding protein, recognizes sequences within the HSV enhancer core. The partially purified C1 factor interacts directly with alpha TIF in the absence of DNA and is required to form a stabile Oct-1/alpha TIF/C1 factor complex. The POU domain of Oct-1 is a bipartite sequence recognition structure, as both the POU-specific box and the POU homeo box contribute directly to the recognition of the octamer element. Surprisingly, the POU homeo box alone is sufficient to direct the cooperative binding of alpha TIF and to assemble the Oct-1/alpha TIF/C1 factor complex.
单纯疱疹病毒（HSV）蛋白αTIF（VP16）的反式激活依赖于一个可诱导的增强子序列，该序列包含八聚体元件的同源物。一系列有序的多蛋白复合物可组装在该增强子上，这需要Oct-1、αTIF和另外两个细胞因子（C1和C2）的相互作用。Oct-1与八聚体同源物结合，而αTIF也是一种序列特异性DNA结合蛋白，可识别HSV增强子核心内的序列。部分纯化的C1因子在无DNA的情况下直接与αTIF相互作用，并且是形成稳定的Oct-1/αTIF/C1因子复合物所必需的。Oct-1的POU结构域是一种二分序列识别结构，因为POU特异性盒和POU同源盒都直接参与八聚体元件的识别。令人惊讶的是，单独的POU同源盒就足以指导αTIF的协同结合并组装Oct-1/αTIF/C1因子复合物。
