Regulation of EBV reactivation

描述(申请人提供)：爱泼斯坦-巴尔病毒(EBV)是一种致癌性人类疱疹病毒，与淋巴和上皮性恶性肿瘤有关。EBV的传播和致病依赖于病毒裂解循环的有效激活。EBV裂解循环的主要启动者是即刻早期蛋白Zta(也被称为Zebra、BZLF1和EB1)。Zta是碱性亮氨酸拉链(b-ZIP)DNA结合蛋白家族中的一个非典型成员，其序列与细胞内C/EBP家族相似，功能上与卡波西肉瘤相关疱疹病毒(KSHV)K8蛋白同源。ZTA可以与病毒和细胞基因组中的多个序列元件结合，以刺激转录活性和来源特异性的DNA复制。ZTA还可以盗用为病毒复制创造许可环境所必需的宿主因素。Zta与裂解周期DNA复制的病毒起源(OriLyt)结合并使病毒复制体成核的能力表明，它是EBV起源结合蛋白(OBP)，很可能与α和β疱疹病毒OBP UL9具有相同的性质。新的初步数据表明，Zta具有单链DNA结合活性，并能识别形成于OriLyt必需上游元件的DNA发夹。ZTA和UL9一样，具有高度保守和氧化还原敏感的半胱氨酸残基，对于复制功能和单链DNA结合是必不可少的。氧化还原敏感的半胱氨酸也是激活C/EBP2所必需的，C/EBP2是KSHV裂解起源复制体的核心细胞因子。在这一应用中，我们建议研究Zta在重新激活EBV裂解复制过程中的生物化学、调控和基因组生物学。我们将测试最重要的假设，即Zta与其他疱疹病毒OBP具有相同的生化和功能特性，并且这些共同特性对于调节和启动裂解复制是必不可少的。

DESCRIPTION (provided by applicant): Epstein-Barr virus (EBV) is an oncogenic human herpesvirus that has been linked to lymphoid and epithelial malignancies. The propagation and pathogenesis of EBV depends on the efficient activation of the viral lytic cycle. The primary initiator of the EBV lytic cycle is the immediate early protein Zta (also referred to as ZEBRA, BZLF1, and EB1). Zta is an atypical member of the basic-leuzine zipper (b-zip) family of DNA binding proteins with sequence similarity to the cellular C/EBP family, and functional homology with the Kaposi's Sarcoma Associated Herpesvirus (KSHV) K8 protein. Zta can bind to multiple sequence elements in the viral and cellular genome to stimulate transcription activity and origin-specific DNA replication. Zta can also pirate host factors necessary to create a permissive environment for viral replication. The ability of Zta to bind the viral origin of lytic cycle DNA replication (OriLyt) and nucleate a viral replisome suggests that is the EBV origin binding protein (OBP), and likely to share properties with the alpha and beta herpesvirus OBP UL9. New preliminary data indicates that Zta possesses single stranded DNA binding activity and can recognize a DNA hairpin that forms at the essential upstream element of OriLyt. Zta, like UL9, have a highly conserved and redox sensitive cysteine residue that is essential for replication function and single strand DNA binding. A redox sensitive cysteine is also essential for activation of C/EBP 2, a cellular factor that nucleates the KSHV lytic origin replisome. In this application, we propose to investigate the biochemistry, regulation, and genome biology of Zta in the reactivation of EBV lytic replication. We will test the overarching hypothesis that Zta shares biochemical and functional properties with other herpesvirus OBPs and that these common properties are essential for regulation and initiation of lytic replication.