Structural Studies of HIV Vif and Its Cellular Binding Partners

描述(由申请人提供)：人类抗病毒蛋白APOBEC3G可诱导广泛的突变并防止艾滋病毒DNA的积累，使病毒不具传染性。为了逃避这种宿主防御机制，HIV表达病毒粒子传染性因子(Vif)。VIF模拟多组分细胞泛素连接酶中的底物受体，并将连接酶招募到多泛素化APOBEC3G以进行蛋白酶体介导的降解。通过与APOBEC3G以及泛素连接酶组分ElonginB/ElonginC和Cullin5的直接相互作用，Vif使HIV能够逃避先天免疫反应的一个关键因素。我们的总体目标是建立HIV Vif隔离APOBEC3G的结构原则，并提供Vif和宿主细胞蛋白之间相互作用的结构细节。我们将确定HIV Vif与其各种细胞结合伙伴的复合体以及Vif/APOBEC3G/泛素连接酶的完整复合体的晶体结构。具体地说，我们将研究包含I)Vif-ElonginB/ElonginC，II)Vif-Cullin5和III)Vif-APOBEC3G相互作用的络合物的结构。从这些研究中获得的结构信息将提供对HIV VIF劫持宿主泛素连接酶以规避APOBEC3G先天免疫反应的机制的深入理解。此外，结构细节将使Vif抑制剂的合理设计成为可能，从而可能导致针对HIV感染的新的治疗干预措施。

DESCRIPTION (provided by applicant): Human antiviral protein APOBEC3G induces extensive mutations and prevents the accumulation of HIV DNA rendering the virus non-infectious. To evade this host defense mechanism, HIV expresses the virion infectivity factor (Vif). Vif mimics the substrate receptor in a multi-component cellular ubiquitin ligase and recruits the ligase to polyubiquitinate APOBEC3G for proteasome-mediated degradation. Through direct interactions with APOBEC3G and the ubiquitin ligase components ElonginB/ElonginC and Cullin5, Vif enables HIV to escape a key element of the innate immune response. Our overall goal is to establish the structural principles by which HIV Vif sequesters APOBEC3G and to provide structural details of the interactions between Vif and host cellular proteins. We will determine the crystal structures of HIV Vif in complex with its various cellular binding partners as well as a complete complex of Vif/APOBEC3G/ubiquitin ligase. Specifically, we will examine the structures of complexes that contain i) the Vif-ElonginB/ElonginC, ii) the Vif-Cullin5, and iii) the Vif- APOBEC3G interactions. Structural information gained from these studies will provide an in-depth understanding of the mechanism by which HIV Vif hijacks the host ubiquitin ligase to circumvent the innate immune response from APOBEC3G. Further, the structural details will enable the rational design of Vif inhibitors that might lead to new therapeutic interventions for HIV infection.