Structure of the Retroviral Restriction Factor, TRIM5alpha

描述(由申请人提供)：灵长类动物表达显性限制因子，在病毒进入宿主细胞后不久但在逆转录之前就能阻止某些逆转录病毒的感染。逆转录病毒衣壳是限制敏感性的决定因素。TRIM5a或在某些物种中，TRIMCyp介导EARL阻断灵长类细胞中的逆转录病毒感染。TRIM5a是三方基序(TRIM)家族的一员，含有环、B-盒2和螺旋卷曲结构域。TRIM5a还含有一个羧基末端的B30.2/spry结构域，已被证明有助于衣壳识别。不同灵长类动物TRIM5a蛋白B30.2/spry结构域的差异解释了观察到的逆转录病毒限制模式。例如，人类免疫缺陷病毒(HIV-1)是导致获得性免疫缺陷综合征(AIDS)的原因，它受到来自旧大陆猴子的TRIM5a蛋白的有效限制，但仅受到人类TRIM5a的适度抑制。人TRIM5a B30.2结构域可变区中的单个精氨酸残基降低了与HIV-1衣壳的亲和力，导致限制性减弱。了解TRIM5a识别衣壳的结构基础可能会提出增强这种对逆转录病毒的固有细胞内免疫的方法。这项工作的总体目标是了解灵长类TRIM5a和TRIMCyp蛋白的结构，并研究它们与组装的逆转录病毒衣壳的相互作用。这项工作的具体目的是：1)建立和优化灵长类TRIM5a和TRIMCyp蛋白的表达系统；2)创造适合结构分析的TRIM5a和TRIMCyp片段；3)鉴定和鉴定能够促进结晶的TRIM5a配体。人类免疫缺陷病毒(HIV)不能感染猴子，因为这些动物会产生一种名为TRIM5pha的抵抗因子。人类TRIM5阿尔法只能适度地阻断艾滋病毒。这项拟议的工作将试图获得TRIM5Alpha的详细图像，以便其抗HIV活性能够得到改善。

DESCRIPTION (provided by applicant): Primates express dominant restriction factors that block the infection of certain retroviruses soon after the virus enters the host cell but prior to reverse transcription. The retroviral capsid is the determinant of susceptibility to restriction. TRIM5a or, in some species, TRIMCyp mediates the earl blocks to retroviral infection in primate cells. TRIM5a is a member of the tripartite motif (TRIM) family of proteins and contains RING, B-box 2 and coiled-coil domains. TRIM5a also contains a carboxy-terminal B30.2/SPRY domain, which has been shown to contribute to capsid recognition. Differences among the B30.2/SPRY domains of TRIM5a proteins from different primate species account for the observed patterns of retroviral restriction. For example, human immunodeficiency virus (HIV-1), the cause of acquired immunodeficiency syndrome (AIDS), is potently restricted by the TRIM5a protein from Old World monkeys, but only modestly inhibited by human TRIM5a. A single arginine residue within a variable region of the human TRIM5a B30.2 domain decreases the affinity for the HIV-1 capsid, resulting in a diminution of restriction. An understanding of the structural basis of capsid recognition by TRIM5a may suggestion approaches to potentiate this innate intracellular immunity to retroviruses. The overall goal of the work proposed is to understand the structure of primate TRIM5a and TRIMCyp proteins and to investigate their interaction with the assembled retroviral capsid. The specific aims of this proposed are: 1) To establish and optimize systems for the expression of primate TRIM5a and TRIMCyp proteins; 2) To create TRIM5a and TRIMCyp fragments that are suitable for structural analysis; 3) To identify and characterize ligands for TRIM5a that could promote crystallization. Human immunodeficiency virus (HIV) cannot infect monkeys because these animals make a resistance factor called TRIM5alpha. Human TRIM5alpha only modestly blocks HIV. The proposed work will attempt to obtain a detailed picture of TRIM5alpha so that its anti-HIV activity could be improved.