High throughput screen identifies natural product inhibitor of phenylalanyl-tRNA synthetase from Pseudomonas aeruginosa and Streptococcus pneumoniae

Authors

• Yanmei Hu, The University of Texas Rio Grande Valley
• Stephanie O. Palmer, The University of Texas Rio Grande Valley
• Hector Munoz, The University of Texas Rio Grande Valley
• James M. Bullard, The University of Texas Rio Grande ValleyFollow

Document Type

Article

Publication Date

5-1-2015

Abstract

Pseudomonas aeruginosa and Streptococcus pneumoniae are causative agents in a wide range of infections. Genes encoding proteins corresponding to phenylalanyl-tRNA synthetase (PheRS) were cloned from both bacteria. The two forms of PheRS were kinetically evaluated and the Km's for P. aeruginosa PheRS with its three substrates, phenylalanine, ATP and tRNA^Phe were determined to be 48, 200, and 1.2 μM, respectively, while the Km's for S. pneumoniae PheRS with respect to phenylalanine, ATP and tRNA^Phe were 21, 225 and 0.94 μM, respectively. P. aeruginosa and S. pneumoniae PheRS were used to screen a natural compound library and a single compound was identified that inhibited the function of both enzymes. The compound inhibited P. aeruginosa and S. pneumoniae PheRS with IC50's of 2.3 and 4.9 μM, respectively. The compound had a Ki of 0.83 and 0.98 μM against P. aeruginosa and S. pneumoniae PheRS, respectively. The minimum inhibitory concentration (MIC) of the compound was determined against a panel of Gram positive and negative bacteria including efflux pump mutants and hyper-sensitive strains. MICs against wild-type P. aeruginosa and S. pneumoniae cells in culture were determined to be 16 and 32 μg/ml, respectively. The mechanism of action of the compound was determined to be competitive with the amino acid, phenylalanine, and uncompetitive with ATP. There was no inhibition of cytoplasmic protein synthesis, however, partial inhibition of the human mitochondrial PheRS was observed.

Recommended Citation

Hu, Yanmei, Stephanie O Palmer, Hector Munoz, and James M Bullard. "High throughput screen identifies natural product inhibitor of phenylalanyl-tRNA synthetase from Pseudomonas aeruginosa and Streptococcus pneumoniae." Current drug discovery technologies 11, no. 4 (2014): 279-292. https://doi.org/10.2174/1570163812666150120154701

First Page

279

Last Page

292

Publication Title

Current Drug Discovery Technologies

DOI

10.2174/1570163812666150120154701