Inositol Polyphosphates and HIV-1 Maturation

项目摘要/摘要 复制艾滋病毒-1，获得性免疫缺陷综合征(AIDS)的病原体，涉及 由Gag多蛋白组成的未成熟颗粒的组装和这些颗粒的随后成熟 通过蛋白水解性切割。虽然HIV-1感染可以通过明智的 服用抗病毒药物，治疗是不能治愈的，耐药性是一个持续令人担忧的问题。从公理上讲， HIV-1病毒在其复制周期的每个阶段都依赖于与宿主细胞分子的相互作用。尽管许多人 这些病毒与宿主之间的相互作用发生在宿主细胞代谢物六磷酸肌醇(Ip6)的蛋白质之间。 最近成为参与HIV-1复制的关键宿主分子。IP6似乎与插嘴结合在一起 感染细胞中的多蛋白，从而稳定Gag六聚体晶格，促进病毒粒子组装。 值得注意的是，IP6还在体外与切割的病毒CA蛋白结合，并促进CA自组装成锥体- 类似的结构在形态上类似于天然的HIV-1衣壳。基于这些观察，一个模型 已经提出，在HIV-1期间，IP6是在被病毒蛋白酶裂解Gag晶格时释放的 成熟。IP6的释放允许其与组装的CA六聚体结合，从而稳定成熟的衣壳 晶格。在这个项目中，我们将验证该模型的关键预测。使用新颖和灵敏的分析方法来 定量与纯化的亚病毒复合体相关的IP5和IP6的水平，我们将确定特定的 GAG多聚蛋白中的裂解是这些配体从未成熟的GAG晶格中解离所需的。 其次，我们将确定IP6与成熟衣壳晶格结合的分子决定因素，包括测试 Arg18在CA中的作用已被证明在体外与IP6形成离子相互作用。最后，我们将量化 IP6水平存在于不同逆转录病毒的颗粒中，这是了解 在其复制周期中利用IP6的逆转录病毒。IP6是第一种非核苷酸的宿主细胞代谢物 HIV-1的复制已被证明依赖于。定义IP6在HIV-1成熟过程中的作用机制是 对于理解HIV-1如何利用这种新的病毒-宿主相互作用至关重要。最终，该项目可能会导致 开发新的抗病毒药物，从而扩大可供长期使用的治疗选择 HIV-1感染的管理。

Project Summary/Abstract Replication of HIV-1, the causative agent of Acquired Immune Deficiency Syndrome (AIDS), involves the assembly of immature particles composed of the Gag polyprotein and subsequent maturation of these particles by proteolytic cleavage. Although HIV-1 infection can be effectively controlled through the judicious administration of antiviral drugs, therapy is not curative, and drug resistance is a constant concern. Axiomatically, HIV-1 depends on interactions with host cell molecules at every stage of its replication cycle. Although many of these virus-host interactions occur between proteins, the host cell metabolite inositol hexakisphosphate (IP6) has recently emerged as a key host molecule involved in HIV-1 replication. IP6 appears to bind to the Gag polyprotein in infected cells, thus stabilizing the Gag hexameric lattice and promoting virion assembly. Remarkably, IP6 also binds to the cleaved viral CA protein in vitro and promotes CA self-assembly into cone- like structures that are morphologically similar to native HIV-1 capsids. Based on these observations, a model has been proposed in which IP6 is released upon cleavage of the Gag lattice by the viral protease during HIV-1 maturation. Release of IP6 permits its binding to assembling CA hexamers, thus stabilizing the mature capsid lattice. In this project, we will validate key predictions of this model. Employing novel and sensitive assays to quantify the levels of IP5 and IP6 associated with purified subviral complexes, we will identify the specific cleavages in the Gag polyprotein required for dissociation of these ligands from the immature Gag lattice. Second, we will identify the molecular determinants of IP6 binding to the mature capsid lattice, including testing the role of Arg18 in CA that has been shown to form ionic interactions with IP6 in vitro. Finally, we will quantify the levels of IP6 present in particles of diverse retroviruses as a first step in understanding the range of retroviruses that utilize IP6 in their replication cycles. IP6 is the first non-nucleotide host cell metabolite on which HIV-1 replication has been shown to depend. Defining the mechanism of IP6 action in HIV-1 maturation is essential to understand how HIV-1 exploits this novel virus-host interaction. Ultimately, the project may lead to the development of new antiviral drugs, thus expanding the available therapeutic options for the long-term management of HIV-1 infection.