Bowser Brian S, Morris Stephanie, Song Moon Jung, Sun Ren, Damania Blossom
Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, 27599, USA.
Virology. 2006 May 10;348(2):309-27. doi: 10.1016/j.virol.2006.02.007. Epub 2006 Mar 20.
The K1 gene of Kaposi's sarcoma-associated herpesvirus (KSHV) encodes a 46-kDa transmembrane glycoprotein that possesses transforming properties, initiates signaling pathways in B cells, and prevents apoptosis. Here, we demonstrate a mechanism for activation of the K1 promoter by the Rta transactivator. Electrophoretic mobility shift assay (EMSA) analysis of the K1 promoter demonstrated that purified Rta protein bound to the K1 promoter at three locations, independent of other DNA-binding factors. Transcriptional assays revealed that only two of these Rta DNA-binding sites are functionally significant, and that they could impart Rta responsiveness to a heterologous E4 TATA box promoter. In addition, TATA-binding protein (TBP) bound to a TATA box element located 25 bp upstream of the K1 transcription start site and was also shown to associate with Rta by coimmunoprecipitation analysis. Rta transactivation may therefore be mediated in part through recruitment of TBP to target promoters.
卡波西肉瘤相关疱疹病毒（KSHV）的K1基因编码一种46 kDa的跨膜糖蛋白，该蛋白具有转化特性，可启动B细胞中的信号通路并防止细胞凋亡。在此，我们展示了一种由Rta反式激活因子激活K1启动子的机制。对K1启动子的电泳迁移率变动分析（EMSA）表明，纯化的Rta蛋白在三个位点与K1启动子结合，这与其他DNA结合因子无关。转录分析显示，这些Rta DNA结合位点中只有两个在功能上具有重要意义，并且它们可以赋予异源E4 TATA盒启动子Rta反应性。此外，TATA结合蛋白（TBP）与位于K1转录起始位点上游25 bp处的TATA盒元件结合，并且通过免疫共沉淀分析也显示其与Rta相关联。因此，Rta反式激活可能部分通过将TBP募集到靶启动子来介导。
