Lieberman P M, Hardwick J M, Sample J, Hayward G S, Hayward S D
Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland 21205.
J Virol. 1990 Mar;64(3):1143-55. doi: 10.1128/JVI.64.3.1143-1155.1990.
The BZLF1 or zta immediate-early gene of Epstein-Barr virus (EBV) encodes a 33-kilodalton phosphorylated nuclear protein that is a specific transcriptional activator of the EBV lytic cycle when introduced into latently infected B lymphocytes. We have shown previously that the divergent EBV DSL target promoter contains two zta-response regions, one within the minimal promoter and the other in an upstream lymphocyte-dependent enhancer region. In this study, we used footprinting and gel mobility retardation assays to reveal that bacterially synthesized Zta fusion proteins bound directly to six TGTGCAA-like motifs within DSL. Four of the Zta-binding sites lay adjacent to cellular TATA and CAAT factor-binding sites within the minimal promoter, and two mapped within the enhancer region. Single-copy oligonucleotides containing these Zta-binding sites conferred Zta responsiveness to heterologous promoters. In addition, the Zta protein, which possesses a similar basic domain to the conserved DNA-binding region of the c-Fos, c-Jun, GCN4, and CREB protein family, proved to bind directly to the consensus AP-1 site in the collagenase 12-O-tetradecanoylphorbol-13-acetate response element. Cotransfection with zta also trans activated a target reporter gene containing inserted wild-type 12-O-tetradecanoylphorbol-13-acetate response element oligonucleotides. Cellular AP-1 binding activity proved to be low in latently EBV-infected Raji cells but was induced (together with the Zta protein) after activation of the lytic cycle with 12-O-tetradecanoylphorbol-13-acetate. We conclude that EBV may have captured and modified a cellular gene encoding a c-jun-like DNA-binding protein during its evolutionary divergence from other herpesviruses and that this protein is used to specifically redirect transcriptional activity toward expression of EBV lytic-cycle genes in infected cells.
爱泼斯坦-巴尔病毒（EBV）的BZLF1或zta即刻早期基因编码一种33千道尔顿的磷酸化核蛋白，当将其导入潜伏感染的B淋巴细胞时，它是EBV裂解周期的特异性转录激活因子。我们先前已经表明，不同的EBV DSL靶启动子包含两个zta反应区域，一个在最小启动子内，另一个在上游淋巴细胞依赖性增强子区域。在本研究中，我们使用足迹法和凝胶迁移率阻滞分析来揭示细菌合成的Zta融合蛋白直接结合到DSL内的六个TGTGCAA样基序上。四个Zta结合位点位于最小启动子内的细胞TATA和CAAT因子结合位点附近，另外两个位于增强子区域内。含有这些Zta结合位点的单拷贝寡核苷酸赋予Zta对异源启动子的反应性。此外事实证明，Zta蛋白具有与c-Fos、c-Jun、GCN4和CREB蛋白家族保守DNA结合区域相似的碱性结构域，它能直接结合胶原酶12-O-十四烷酰佛波醇-13-乙酸酯反应元件中的共有AP-1位点。与zta共转染也反式激活了一个包含插入的野生型12-O-十四烷酰佛波醇-13-乙酸酯反应元件寡核苷酸的靶报告基因。在潜伏感染EBV的Raji细胞中，细胞AP-1结合活性较低，但在用12-O-十四烷酰佛波醇-13-乙酸酯激活裂解周期后（与Zta蛋白一起）被诱导。我们得出结论，EBV在与其他疱疹病毒的进化分歧过程中可能捕获并修饰了一个编码c-jun样DNA结合蛋白的细胞基因，并且该蛋白被用于在感染细胞中特异性地将转录活性重新导向EBV裂解周期基因的表达。
