Structural Studies of Human APOBEC3G and HIV Vif

描述（由申请人提供）：人类APOBEC3G能够通过将cDNA胞嘧啶脱胺为尿嘧啶来改变HIV基因组。这种活性可以从基因上灭活HIV。作为一种反防御机制，HIV促进APOBEC3G蛋白的降解。降解需要HIV病毒粒子感染因子（Vif）蛋白与APOBEC3G相互作用。目前的研究已经揭示了这种宿主-病原体冲突的大量遗传和生化细节，但仍然缺乏原子水平的理解。因此，本研究的主要目的是获得APOBEC3G的DNA胞嘧啶脱氨酶活性和APOBEC3G -Vif相互作用的结构理解。这些目标将通过以下具体目标实现：(I)我们将实现对APOBEC3G的原子水平的理解以及它如何催化DNA胞嘧啶脱氨反应；（II）我们将获得原子水平的知识，解释APOBEC3G是如何被Vif识别的。这些主要目标将通过结合遗传、生化、生物物理和结构（NMR）方法来实现。这些研究将产生第一个多核苷酸胞嘧啶脱氨酶的结构，由此产生的结构见解将使我们更接近于实现我们开发增强APOBEC3G功能的治疗方法的长期目标。人类APOBEC3G （A3G）能够通过将cDNA胞嘧啶脱胺为尿嘧啶来改变HIV基因组。这种活动可以从基因上灭活病毒。作为一种反防御机制，HIV促进泛素介导的A3G蛋白降解。降解需要A3G与HIV病毒粒子感染因子（Vif）蛋白相互作用。目前的研究已经揭示了这种宿主-病原体冲突的大量遗传和生化细节，但仍然缺乏原子水平的理解。因此，本研究的主要目的是获得对A3G的DNA胞嘧啶脱氨酶活性和A3G- vif相互作用的结构理解。

DESCRIPTION (provided by applicant): Human APOBEC3G is capable of altering the HIV genome by deaminating cDNA cytosines to uracils. This activity can genetically inactivate HIV. As a counter-defense mechanism, HIV promotes protein degradation of APOBEC3G. Degradation requires that the HIV virion infectivity factor (Vif) protein interacts with APOBEC3G. Current studies have revealed substantial genetic and biochemical details of this host-pathogen conflict, but an atomic level understanding is still lacking. Therefore, the major objectives of this research are to obtain a structural understanding of the DNA cytosine deaminase activity of APOBEC3G and of the APOBEC3G -Vif interaction. These objectives will be achieved through the following specific aims: (I) we will achieve an atomic-level understanding of APOBEC3G and how it catalyzes the DNA cytosine deamination reaction, and (II) we will obtain an atomic-level knowledge that will explain how APOBEC3G is recognized by Vif. These primary objectives will be met by combining genetic, biochemical, biophysical and structural (NMR) approaches. These studies will produce the first structure of a polynucleotide cytosine deaminase, and the resulting structural insights will take us several steps closer to achieve our long-term goal of developing therapeutic methods for enhancing APOBEC3G function. Human APOBEC3G (A3G) is capable of altering the HIV genome by deaminating cDNA cytosines to uracils. This activity can genetically inactivate the virus. As a counter-defense mechanism, HIV promotes the ubiquitin-mediated protein degradation of A3G. Degradation requires that A3G interacts with the HIV virion infectivity factor (Vif) protein. Current studies have revealed substantial genetic and biochemical details of this host-pathogen conflict, but an atomic level understanding is still lacking. Therefore, the major objectives of this research are to obtain a structural understanding of the DNA cytosine deaminase activity of A3G and of the A3G-Vif interaction.