Structural Analysis of Helminth mRNA Cap-Binding Proteins

描述(申请人提供)：寄生蠕虫在世界许多地区仍然是一个严重的公共卫生问题。蠕虫感染20多亿人，可降低儿童的身体和认知发育，导致相当大的发病率，并阻碍流行地区的社会经济发展。新的潜在药物靶点的确定和表征是必要的，因为已经确定了耐药的例子。此外，开发更广泛的光谱靶标和药物将是极其有价值的。一个耐人寻味的潜在靶点是寄生虫翻译起始因子eIF4E。EIF4E识别mRNA上限，是翻译中的关键和速率限制步骤。脊椎动物宿主eIF4E是单甲基鸟苷真核生物帽子的高度特异性，这是脊椎动物mRNAs上唯一存在的帽子。相反，我们已经证明蛔虫和血吸虫eIF4E对三甲基鸟苷帽和单甲基鸟苷帽具有相似的亲和力。因此，与脊椎动物eIF4E相比，寄生蠕虫eIF4E具有识别三甲基鸟苷(TMG)帽的独特能力。寄生蠕虫中的许多mRNAs都有TMG帽。大约10%(血吸虫)到90%(蛔虫)的蠕虫mRNAs通过一种称为剪接前导RNA反式剪接的特殊类型的剪接获得TMG帽。反式剪接产生mRNAs的成熟5‘端，并将特化的TMG帽添加到蠕虫mRNAs中。寄生蠕虫的所有主要类群都表现出剪接前导反式剪接。TMG帽的识别对于线虫mRNAs的翻译是必不可少的，eIF4E在线虫中是必不可少的。为了了解蠕虫eif4E识别TMG帽的生化和生物物理基础，我们建议对TMG帽m2，2，7GpppG结合的蠕虫eif4E进行X射线结晶学和核磁共振研究。这些研究的信息将为寄生虫eIF4E与TMG-CAP结合的关键相互作用和机制提供深入的见解。这些信息将有助于指导合理突变研究，以进一步定义重要的eIF4E-TMG帽相互作用。总体而言，这些研究将确定TMG帽识别的关键特征，这可能使未来的研究能够针对广泛存在于重要蠕虫感染中的eIF4E独特的底物结合属性设计特定的帽类似物。公共卫生相关性：在世界许多地区，寄生虫仍然是一个严重的公共卫生问题，并阻碍流行地区的社会经济发展。我们将对一种重要的寄生虫蛋白eIF4E进行结构分析，该蛋白具有独特的底物特异性，用于mRNA帽，以评估该蛋白作为新的和新的治疗寄生虫的潜在靶点。

DESCRIPTION (provided by applicant): Parasitic helminths remain a significant public health problem in many parts of the world. Helminths infect over 2 billion people, can decrease physical and cognitive development in children, lead to considerable morbidity, and hinder socioeconomic development in endemic areas. The identification and characterization of new potential drug targets is warranted as examples of drug resistance have been identified. In addition, the development of broader spectrum targets and drugs would be extremely valuable. One intriguing potential target is the parasite translation initiation factor eIF4E. eIF4E recognizes the mRNA cap and is a key and rate-limiting step in translation. Vertebrate host eIF4E is highly specific for a monomethylguanosine eukaryotic cap, and this is the only cap present on vertebrate mRNAs. In contrast, we have shown that Ascaris and schistosome eIF4Es have similar affinities for both the trimethyl- and monomethylguanosine caps. Thus, parasitic helminth eIF4Es have the unique ability to recognize trimethylguanosine (TMG) caps compared with their vertebrate eIF4E counterparts. Many mRNAs in parasitic helminths have a TMG cap. Approximately 10% (schistosomes) to 90% (Ascaris) of helminth mRNAs acquire a TMG cap through a special type of splicing known as spliced leader RNA trans-splicing. Trans-splicing generates the mature 5' ends of mRNAs and adds the specialized TMG cap to helminth mRNAs. All major groups of parasitic helminths exhibit spliced leader trans-splicing. Recognition of the TMG cap is essential for translation of helminth mRNAs and eIF4E is essential in C. elegans. To understand the biochemical and biophysical basis for helminth eIF4E recognition of the TMG cap, we propose to carry out X-ray crystallography and NMR studies on helminth eIF4E bound to the TMG cap, m2,2,7GpppG. Information from these studies will provide insight into the key interactions and mechanism of TMG-cap binding by parasite eIF4E. This information will help direct rational mutagenesis studies to further define important eIF4E-TMG cap interactions. Overall, these studies will identify key features of TMG cap recognition that may enable future studies directed at designing specific cap analogs to target the unique substrate binding attributes of eIF4E present in a broad spectrum of important helminth infections. PUBLIC HEALTH RELEVANCE: Parasitic helminths remain a significant public health problem in many parts of the world and hinder socioeconomic development in endemic areas. We will carry out structural analyses of an essential parasite protein, eIF4E, with unique substrate specificity for the mRNA cap to evaluate this protein as a potential target for new and novel therapeutics against parasitic helminths.