Discovery and Characterization of Chemical Compounds That Inhibit the Function of Aspartyl-tRNA Synthetase from Pseudomonas aeruginosa

Identification and Characterization of Chemical Compounds that Inhibit Leucyl-tRNA Synthetase from Pseudomonas aeruginosa

BACKGROUND

Pseudomonas aeruginosa is an opportunistic multi-drug resistance pathogen implicated as the causative agent in a high-percentage of nosocomial and community acquired bacterial infections. The gene encoding leucyl-tRNA synthetase (LeuRS) from P. aeruginosa was overexpressed in Escherichia coli and the resulting protein was characterized.

METHODS

LeuRS was kinetically evaluated and the KM values for interactions with leucine, ATP and tRNA were 6.5, 330, and 3.0 μM, respectively. LeuRS was developed into a screening platform using scintillation proximity assay (SPA) technology and used to screen over 2000 synthetic and natural chemical compounds.

RESULTS

The initial screen resulted in the identification of two inhibitory compounds, BT03C09 and BT03E07. IC50s against LeuRS observed for BT03C09 and BT03E07 were 23 and 15 μM, respectively. The minimum inhibitory concentrations (MIC) were determined against nine clinically relevant bacterial strains. In time-kill kinetic analysis, BT03C09 was observed to inhibit bacterial growth in a bacteriostatic manner, while BT03E07 acted as a bactericidal agent. Neither compound competed with leucine or ATP for binding LeuRS. Limited inhibition was observed in aminoacylation assays with the human mitochondrial form of LeuRS, however when tested in cultures of human cell line, BT03C09 was toxic at all concentration whereas BT03E07 only showed toxic effects at elevated concentrations.

CONCLUSION

Two compounds were identified as inhibitors of LeuRS in a screen of over 2000 natural and synthetic compounds. After characterization one compound (BT03E07) exhibited broad spectrum antibacterial activity while maintaining low toxicity against human mitochondrial LeuRS as well as against human cell cultures.

11th IUBMB Focused Meeting on the Aminoacyl-tRNA Synthetases: Sailing a New Sea of Complex Functions in Human Biology and Disease

The 11th IUBMB Focused Meeting on Aminoacyl-tRNA Synthetases was held in Clearwater Beach, Florida from 29 October–2 November 2017, with the aim of presenting the latest research on these enzymes and promoting interchange among aminoacyl-tRNA synthetase (ARS) researchers. Topics covered in the meeting included many areas of investigation, including ARS evolution, mechanism, editing functions, biology in prokaryotic and eukaryotic cells and their organelles, their roles in human diseases, and their application to problems in emerging areas of synthetic biology. In this report, we provide a summary of the major themes of the meeting, citing contributions from the oral presentations in the meeting.