Agoff S N, Wu B
Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208.
Oncogene. 1994 Dec;9(12):3707-11.
Genetic and biochemical evidence suggest that conserved region 3 (CR3) of the adenovirus Ela polypeptide can provide two distinct and separable functions: an N-terminal transcriptional activation region and a C-terminal promoter targeting region. It is thought that the promoter targeting region of Ela CR3 interacts with promoter-specific transcription factors, thereby bringing the activation region of Ela CR3 in proximity of the promoter. Here we report that CBF, a CCAAT-box-binding factor that regulates hsp70 gene expression and mediates Ela trans-activation in vivo, interacts with the promoter targeting region of Ela CR3 in vitro. Point mutations in Ela CR3 that are defective in stimulating transcription from the hsp70 promoter are also defective in stimulating transcription directed by a synthetic activator, GAL-CBF, composed of the DNA-binding domain of yeast GAL4 fused to CBF. These mutations fall into two classes with respect to their abilities to interact with CBF in vitro. Mutations in the transcriptional activation region of Ela CR3 do not affect binding to CBF, but mutation of the promoter targeting region of Ela CR3 prevents association with CBF in vitro.
遗传学和生物化学证据表明，腺病毒E1a多肽的保守区域3（CR3）可提供两种不同且可分离的功能：一个N端转录激活区域和一个C端启动子靶向区域。据认为，E1a CR3的启动子靶向区域与启动子特异性转录因子相互作用，从而使E1a CR3的激活区域靠近启动子。在此我们报告，CBF是一种调节hsp70基因表达并在体内介导E1a反式激活的CCAAT盒结合因子，它在体外与E1a CR3的启动子靶向区域相互作用。E1a CR3中刺激hsp70启动子转录有缺陷的点突变，在刺激由与CBF融合的酵母GAL4的DNA结合结构域组成的合成激活剂GAL-CBF指导的转录时也有缺陷。就它们在体外与CBF相互作用的能力而言，这些突变分为两类。E1a CR3转录激活区域的突变不影响与CBF的结合，但E1a CR3启动子靶向区域的突变会阻止其在体外与CBF结合。
