title: Selective inhibitors of methionyl-tRNA synthetase have potent activity against Trypanosoma brucei Infection in Mice.
abstract: Human African trypanosomiasis continues to be an important public health threat in extensive regions of sub-Saharan Africa. Treatment options for infected patients are unsatisfactory due to toxicity, difficult administration regimes, and poor efficacy of available drugs. The aminoacyl-tRNA synthetases were selected as attractive drug targets due to their essential roles in protein synthesis and cell survival. Comparative sequence analysis disclosed differences between the trypanosome and mammalian methionyl-tRNA synthetases (MetRSs) that suggested opportunities for selective inhibition using drug-like molecules. Experiments using RNA interference on the single MetRS of Trypanosoma brucei demonstrated that this gene product was essential for normal cell growth. Small molecules (diaryl diamines) similar to those shown to have potent activity on prokaryotic MetRS enzymes were synthesized and observed to have inhibitory activity on the T. brucei MetRS (50% inhibitory concentration, <50 nM) and on bloodstream forms of T. brucei cultures (50% effective concentration, as low as 4 nM). Twenty-one compounds had a close correlation between enzyme binding/inhibition and T. brucei growth inhibition, indicating that they were likely to be acting on the intended target. The compounds had minimal effects on mammalian cell growth at 20 μM, demonstrating a wide therapeutic index. The most potent compound was tested in the murine model of trypanosomiasis and demonstrated profound parasite suppression and delayed mortality. A homology model of the T. brucei MetRS based on other MetRS structures was used to model binding of the lead diaryl diamine compounds. Future studies will focus on improving the pharmacological properties of the MetRS inhibitors.
authors.affiliation: Department of Biochemistry, University of Washington, Division of Allergy and Infectious Diseases, Box 357185, Seattle, WA 98195, USA.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Shibata
authors.forename: J Robert
authors.initials: JR
authors.lastname: Gillespie
authors.forename: Angela M
authors.initials: AM
authors.lastname: Kelley
authors.forename: Alberto J
authors.initials: AJ
authors.lastname: Napuli
authors.forename: Zhongsheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Kuzma V
authors.initials: KV
authors.lastname: Kovzun
authors.forename: Ranae M
authors.initials: RM
authors.lastname: Pefley
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Lam
authors.forename: Frank H
authors.initials: FH
authors.lastname: Zucker
authors.forename: Wesley C
authors.initials: WC
authors.lastname: Van Voorhis
authors.forename: Ethan A
authors.initials: EA
authors.lastname: Merritt
authors.forename: Wim G J
authors.initials: WG
authors.lastname: Hol
authors.forename: Christophe L M J
authors.initials: CL
authors.lastname: Verlinde
authors.forename: Erkang
authors.initials: E
authors.lastname: Fan
authors.forename: Frederick S
authors.initials: FS
authors.lastname: Buckner
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D049109:Cell Proliferation / Q000187:drug effects; D003959:Diamines / Q000494:pharmacology; D008718:Methionine-tRNA Ligase / Q000037:antagonists & inhibitors*; D051379:Mice; D008807:Mice, Inbred BALB C; D016133:Polymerase Chain Reaction; D034622:RNA Interference; D014344:Trypanocidal Agents / Q000627:therapeutic use; D014346:Trypanosoma brucei brucei / Q000187:drug effects* / Q000201:enzymology
chemical_list: D003959:Diamines; D014344:Trypanocidal Agents; D008718:Methionine-tRNA Ligase