Selective inhibition of tRNA synthetases from pathogenic protozoa

描述(申请人提供)：本项目重点研究三种主要的全球致病原虫，布氏锥虫、克氏锥虫和利什曼原虫的基本蛋白质。这些寄生虫分别导致昏睡病、恰加斯病和利什曼病，每年造成数千万人感染，主要发生在世界热带和亚热带地区。这些复杂的原虫能够避开宿主的防御系统，给患者带来长期的痛苦。为数不多的几种药物都有严重的副作用，耐药性问题正在上升。这项提案针对这些真核生物共有的关键生物途径，解决了开发新疗法的需要。这一战略将通过使用相同的抑制物支架来促进这三种原生动物的药物开发。具体地说，三个在活细胞中蛋白质合成必不可少的氨基酰基-tRNA合成酶(AARs)家族将通过整合基于结构的和化合物文库筛选方法而成为目标。这些方法包括：(I)基于已知的针对其他病原体的AARS抑制剂(其中一些对锥虫的抑制效果比人类细胞好几个数量级)的“背负式”抑制剂开发，(Ii)高通量化学文库的高通量溶液筛选，(Iii)碎片鸡尾酒结晶学，以及(Iv)计算化学。复合打击将受到几轮优化，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基于细胞的测试进行评估，以评估有效性、选择性和毒性。该项目的目标是为目标的五种AARS酶获得一到两种亚微摩尔抑制剂。这些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.