Structural Studies of Human APOBEC3G and HIV Vif

描述（由申请人提供）：人APOBEC 3G能够通过将cDNA胞嘧啶脱氨为尿嘧啶来改变HIV基因组。这种活动可以遗传HIV。作为一种反防御机制，HIV促进APOBEC 3G的蛋白质降解。降解需要HIV病毒体感染因子（Vif）蛋白与APOBEC 3G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APOBEC 3G的DNA胞嘧啶脱氨酶活性和APOBEC 3G-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APOBEC 3G的原子级理解以及它如何催化DNA胞嘧啶脱氨基反应，（II）我们将获得原子级知识，解释Vif如何识别APOBEC 3G。这些主要目标将通过结合遗传、生物化学、生物物理和结构（NMR）方法来实现。这些研究将产生多核苷酸胞嘧啶脱氨酶的第一个结构，由此产生的结构见解将使我们更接近实现我们开发增强APOBEC 3G功能的治疗方法的长期目标。人APOBEC 3G（A3 G）能够通过将cDNA胞嘧啶脱氨基为尿嘧啶来改变HIV基因组。这种活动可以从基因上抑制病毒。作为一种反防御机制，HIV促进A3 G的泛素介导的蛋白质降解。降解需要A3 G与HIV病毒体感染因子（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，本研究的主要目标是获得A3 G的DNA胞嘧啶脱氨酶活性和A3 G-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.