Selective inhibition of tRNA synthetases from pathogenic protozoa

描述（由申请人提供）：该项目的重点是三种主要的全球致病性原生动物，布氏锥虫，克氏锥虫和利什曼原虫物种的必需蛋白质。这些是相关的寄生虫，分别引起昏睡病、恰加斯病和利什曼病，每年造成数千万人感染，主要发生在世界的热带和亚热带地区。这些复杂的原生动物能够避开宿主的防御系统，并给患者造成长期的痛苦。现有的少数药物具有严重的副作用，耐药性问题正在上升。该提案通过靶向这些真核生物共有的关键生物学途径来解决开发新疗法的需求。这一策略将通过使用相同的抑制剂支架来促进跨越三种原生动物的药物开发。 具体而言，三个氨酰-tRNA合成酶（阿尔斯）的家庭是必不可少的蛋白质合成活细胞将有针对性的整合结构为基础的化合物库筛选方法。这些方法包括：（i）基于已知的用于其它病原体的阿尔斯抑制剂的“背负式”抑制剂开发（其中一些抑制锥虫比人细胞好几个数量级），（ii）化学文库的高通量溶液筛选，（iii）晶体学上的片段混合物，和（iv）计算化学。化合物命中将经历多轮优化，以通过基于结构的设计提高效力和选择性。新合成的抑制剂将通过基于酶和细胞的试验进行评价，以评估疗效、选择性和毒性。该项目的目标是为五种靶向阿尔斯酶找到一种或两种亚微摩尔抑制剂。这将为随后的药物开发工作提供新的起点。

DESCRIPTION (provided by applicant): This project focuses on essential proteins from three major global pathogenic protozoa, Trypanosoma brucei, Trypanosoma cruzi and Leishmania species. These are related parasites which cause sleeping sickness, Chagas disease, and leishmaniasis, respectively, and are responsible for tens of millions of infections annually, mainly in the tropical and subtropical areas of the world. These sophisticated protozoa are able to avoid the host defense systems, and cause prolonged suffering for the patients. The few drugs that are available have serious side-effects and drug resistance problems are rising. This proposal addresses the need for developing new therapeutics by targeting a critical biological pathway shared by these eukaryotic organisms. This strategy will facilitate drug development across the three protozoa by using the same inhibitor scaffolds. Specifically, three aminoacyl-tRNA synthetase (aaRS) families that are essential for protein synthesis in living cells will be targeted by integrating structure-based and compound library screening methodologies. The approaches include: (i) "piggyback" inhibitor development based on known aaRS inhibitors for other pathogens (some of which inhibit trypanosomatids several orders of magnitude better than human cells), (ii) high throughput solution screening of chemical libraries, (iii) fragment cocktail crystallographically, and (iv) computational chemistry. Compound hits will be subjected to rounds of optimization to improve potency and selectivity by structure-based design. Newly synthesized inhibitors will be evaluated by enzyme and cell-based assays to assess efficacy, selectivity and toxicity. The goal of this project is to arrive at one or two submicromolar inhibitors for five of the aaRS enzymes targeted. These would provide new starting points for subsequent drug development efforts.