Retroviral capsid recognition by TRIM5alpha restriction factors

描述：TRIM5α限制性因子在细胞进入后结合逆转录病毒衣壳，并通过阻断逆转录和/或病毒遗传物质的整合来限制逆转录病毒感染。TRIM5α的c端SPRY结构域被认为形成了大部分的衣壳-TRIM5α界面，因为SPRY结构域内的物种特异性序列差异解释了TRIM5α介导的限制性反应的病毒特异性差异。最值得注意的是，最近人类TRIM5α SPRY基因的进化导致了这种变异对HIV衣壳的亲和力较差，当猴免疫缺陷病毒（SIV）从黑猩猩传播到人类宿主时，这种脆弱性导致了艾滋病大流行的出现。SPRY结构域中单个氨基酸残基（R332）的突变或缺失可恢复人类TRIM5α变异体对HIV的限制。TRIM5α SPRY结构域已被证明对结构和生物物理研究具有难降解性，限制了我们对TRIM5α识别逆转录病毒衣壳的理解。本研究计划试图通过解决几种具有不同逆转录病毒特异性的灵长类TRIM5α SPRY变异的结构并表征它们与同源逆转录病毒衣壳的相互作用来填补这一知识空白。本研究的目的是了解TRIM5α限制因子对衣壳识别的机制，阐明为什么人类TRIM5α变体对HIV无效，并探索是否可以通过药物或其他手段减轻这种缺陷。以下三个具体目标将追求：(1)将使用结合核磁共振波谱和x射线晶体学的新颖实验方法来解决恒河，人类和可能的其他TRIM5α SPRY结构域的结构。(2)几个spry -衣壳对的相互作用将使用各种生物物理方法进行表征。(3) spry -衣壳复合物的高分辨率模型将使用计算方法生成，并使用诱变和限制性分析进行测试。

DESCRIPTION: TRIM5α restriction factors bind retroviral capsids after cell entry and restrict retroviral infection by blocking reverse transcription and/or integration of the viral genetic material. The C-terminal SPRY domain of TRIM5α is believed to form most of the capsid-TRIM5α interface as species-specific sequence variations within the SPRY domain account for differences in the viral specificity of the TRIM5α-mediated restriction. Most notably, recent evolution of the human TRIM5α SPRY resulted in the variant that has poor affinity for the HIV capsid, the vulnerability that contributed to the emergence of the AIDS pandemic when the simian immunodeficiency virus (SIV) passed from chimpanzees into a human host. Mutation or deletion of a single amino acid residue (R332) within the SPRY domain restores HIV restriction by the human TRIM5α variant. TRIM5α SPRY domains have proven refractory to structural and biophysical studies limiting our understanding of retroviral capsid recognition by TRIM5α. This research proposal seeks to fill that knowledge gap by solving the structures of several primate TRIM5α SPRY variants with distinct retroviral specificities and characterizing their interactions with the cognate retroviral capsids. The goal of the proposed research is to understand the mechanism of capsid recognition by TRIM5α restriction factors, elucidate why the human TRIM5α variant is not potent against HIV and to explore whether this defect could be alleviated by pharmacological or other means. The following three specific aims will be pursued: (1) The structures of the rhesus, human and possibly other TRIM5α SPRY domains will be solved using a novel experimental approach that combines NMR spectroscopy and X-ray crystallography. (2) Interaction of several SPRY-capsid pairs will be characterized using a variety of biophysical approaches. (3) High-resolution models of the SPRY-capsid complexes will be generated using computational methods and tested using mutagenesis and restriction assays.