Identification and Characterization of a Chemical Compound that Inhibits Methionyl-tRNA Synthetase from Pseudomonas aeruginosa

Title:Identification and Characterization of a Chemical Compound that Inhibits Methionyl-tRNA Synthetase from Pseudomonas aeruginosa

Volume: 14 Issue: 3

Author(s): Sara Robles, Yanmei Hu, Tahyra Resto, Frank Dean and James M. Bullard*

Affiliation:

• Chemistry Department, SCNE. 3.320, The University of Texas-RGV, 1201 W. University Drive, Edinburg, TX 78541,United States

Keywords: Protein synthesis, in vitro screening, tRNA aminoacylation, drug discovery, antibiotics, Pseudomonas.

Abstract: Background: Pseudomonas aeruginosa is an opportunistic pathogen problematic in causing nosocomial infections and is highly susceptible to development of resistance to multiple antibiotics. The gene encoding methionyl-tRNA synthetase (MetRS) from P. aeruginosa was cloned and the resulting protein characterized.

Methods: MetRS was kinetically evaluated and the K_M for its three substrates, methionine, ATP and tRNA^Met were determined to be 35, 515, and 29 μM, respectively. P. aeruginosaMetRS was used to screen two chemical compound libraries containing 1690 individual compounds.

Results: A natural product compound (BM01C11) was identified that inhibited the aminoacylation function. The compound inhibited P. aeruginosa MetRS with an IC₅₀ of 70 μM. The minimum inhibitory concentration (MIC) of BM01C11 was determined against nine clinically relevant bacterial strains, including efflux pump mutants and hypersensitive strains of P. aeruginosa and E. coli. The MIC against the hypersensitive strain of P. aeruginosa was 16 μg/ml. However, the compound was not effective against the wild-type and efflux pump mutant strains, indicating that efflux may not be responsible for the lack of activity against the wild-type strains. When tested in human cell cultures, the cytotoxicity concentration (CC₅₀) was observed to be 30 μg/ml. The compound did not compete with methionine or ATP for binding MetRS, indicating that the mechanism of action of the compound likely occurs outside the active site of aminoacylation.

Conclusion: An inhibitor of P. aeruginosa MetRS, BM01C11, was identified as a flavonoid compound named isopomiferin. Isopomiferin inhibited the enzymatic activity of MetRS and displayed broad spectrum antibacterial activity. These studies indicate that isopomiferin may be amenable to development as a therapeutic for bacterial infections.

Cite this article as:

Robles Sara , Hu Yanmei, Resto Tahyra , Dean Frank and Bullard M. James *, Identification and Characterization of a Chemical Compound that Inhibits Methionyl-tRNA Synthetase from Pseudomonas aeruginosa, Current Drug Discovery Technologies 2017; 14 (3) . https://dx.doi.org/10.2174/1570163814666170330100238

DOI https://dx.doi.org/10.2174/1570163814666170330100238	Print ISSN 1570-1638
Publisher Name Bentham Science Publisher	Online ISSN 1875-6220