Selective inhibition of tRNA synthetases from pathogenic protozoa

项目描述（申请人提供）：本项目主要研究全球三大致病性原生动物——布鲁氏锥虫、克氏锥虫和利什曼原虫的必需蛋白。这些是相关寄生虫，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，给病人造成长期的痛苦。少数可用的药物有严重的副作用，耐药性问题正在上升。该建议通过针对这些真核生物共享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促进三种原生动物的药物开发。具体来说，三个对活细胞中蛋白质合成至关重要的氨基酰基trna合成酶（aaRS）家族将通过整合基于结构和化合物文库筛选方法来靶向。这些方法包括：(i)基于已知的用于其他病原体的aaRS抑制剂（其中一些对锥虫的抑制比人类细胞好几个数量级）的“搭便车”抑制剂开发，（ii）化学文库的高通量溶液筛选，（iii）片段鸡尾酒晶体学，以及（iv）计算化学。化合物命中将受到一轮轮的优化，以提高效力和选择性的结构为基础的设计。新合成的抑制剂将通过酶和细胞为基础的实验来评估其有效性、选择性和毒性。该项目的目标是针对5种aaRS酶获得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. PUBLIC HEALTH RELEVANCE: The research is directly relevant to the development of therapeutic agents for major, yet largely neglected, diseases occurring in tropical and subtropical areas, threatening hundreds of millions of people. Highly potent compounds that selectively inhibit protein synthesis in pathogenic protozoa will be optimized using structure-based drug design methods.