Kerry J A, Priddy M A, Stenberg R M
Department of Microbiology and Immunology, Eastern Virginia Medical School, Norfolk 23501.
J Virol. 1994 Jul;68(7):4167-76. doi: 10.1128/JVI.68.7.4167-4176.1994.
To determine the mechanisms involved in the regulation of human cytomegalovirus early gene expression, we have examined the gene that encodes the viral DNA polymerase (UL54, pol). Our previous studies demonstrated that sequences required for activation of the pol promoter by immediate-early proteins are contained within a region from -128 to +20 and that cellular proteins can bind to this activation domain. In this study, we demonstrate by competition analysis that binding of cellular proteins to pol is associated with an 18-bp region containing a single copy of a novel inverted repeat, IR1. Time course analysis indicated that viral infection increased the level of protein binding to IR1, concurrent with the activation of the pol promoter. Mutation of the IR1 element abrogated binding of cellular factors to the pol promoter and reduced by threefold the activation by immediate-early proteins. Similarly, mutation of IR1 rendered the promoter poorly responsive to activation by viral infection. Mutation of additional sequence elements in the pol promoter had little effect, indicating that IR1 plays the major role in pol promoter regulation. These studies demonstrate that the interaction between cellular factors and IR1 is important for the regulation of expression of the polymerase gene by viral proteins.
为了确定参与人类巨细胞病毒早期基因表达调控的机制，我们研究了编码病毒DNA聚合酶（UL54，pol）的基因。我们之前的研究表明，立即早期蛋白激活pol启动子所需的序列包含在从-128到+20的区域内，并且细胞蛋白可以结合到这个激活域。在本研究中，我们通过竞争分析证明，细胞蛋白与pol的结合与一个包含新型反向重复序列IR1单拷贝的18bp区域相关。时间进程分析表明，病毒感染增加了与IR1结合的蛋白水平，同时伴随着pol启动子的激活。IR1元件的突变消除了细胞因子与pol启动子的结合，并使立即早期蛋白的激活降低了三倍。同样，IR1的突变使启动子对病毒感染激活的反应性很差。pol启动子中其他序列元件的突变影响很小，表明IR1在pol启动子调控中起主要作用。这些研究表明，细胞因子与IR1之间的相互作用对于病毒蛋白调控聚合酶基因的表达很重要。
