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.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
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Mcgugan, Glen C
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University of Washington
Schools of Medicine
United States
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Zhang, Zhongsheng; Koh, Cho Yeow; Ranade, Ranae M et al. (2016) 5-Fluoroimidazo[4,5-b]pyridine Is a Privileged Fragment That Conveys Bioavailability to Potent Trypanosomal Methionyl-tRNA Synthetase Inhibitors. ACS Infect Dis 2:399-404
Huang, Wenlin; Zhang, Zhongsheng; Barros-Álvarez, Ximena et al. (2016) Structure-guided design of novel Trypanosoma brucei Methionyl-tRNA synthetase inhibitors. Eur J Med Chem 124:1081-1092
Koh, Cho Yeow; Siddaramaiah, Latha Kallur; Ranade, Ranae M et al. (2015) A binding hotspot in Trypanosoma cruzi histidyl-tRNA synthetase revealed by fragment-based crystallographic cocktail screens. Acta Crystallogr D Biol Crystallogr 71:1684-98
Pedró-Rosa, Laura; Buckner, Frederick S; Ranade, Ranae M et al. (2015) Identification of potent inhibitors of the Trypanosoma brucei methionyl-tRNA synthetase via high-throughput orthogonal screening. J Biomol Screen 20:122-30
Ranade, Ranae M; Zhang, Zhongsheng; Gillespie, J Robert et al. (2015) Inhibitors of methionyl-tRNA synthetase have potent activity against Giardia intestinalis trophozoites. Antimicrob Agents Chemother 59:7128-31
Koh, Cho Yeow; Wetzel, Allan B; de van der Schueren, Will J et al. (2014) Comparison of histidine recognition in human and trypanosomatid histidyl-tRNA synthetases. Biochimie 106:111-20
Koh, Cho Yeow; Kim, Jessica E; Wetzel, Allan B et al. (2014) Structures of Trypanosoma brucei methionyl-tRNA synthetase with urea-based inhibitors provide guidance for drug design against sleeping sickness. PLoS Negl Trop Dis 8:e2775
Koh, Cho Yeow; Kim, Jessica E; Napoli, Alberto J et al. (2013) Crystal structures of Plasmodium falciparum cytosolic tryptophanyl-tRNA synthetase and its potential as a target for structure-guided drug design. Mol Biochem Parasitol 189:26-32
Ranade, Ranae M; Gillespie, J Robert; Shibata, Sayaka et al. (2013) Induced resistance to methionyl-tRNA synthetase inhibitors in Trypanosoma brucei is due to overexpression of the target. Antimicrob Agents Chemother 57:3021-8
Shibata, Sayaka; Gillespie, J Robert; Ranade, Ranae M et al. (2012) Urea-based inhibitors of Trypanosoma brucei methionyl-tRNA synthetase: selectivity and in vivo characterization. J Med Chem 55:6342-51

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