Development and characterization of a Pseudomonas aeruginosa in vitro coupled transcription–translation assay system for evaluation of translation inhibitors

Bacterial transcription and translation have proven to be effective targets for broad-spectrum antimicrobial therapies owing to the critical role they play in bacterial propagation and the overall conservation of the associated machinery involved. Escherichia coli is the most common source of S30 extract used in bacterial in vitro coupled transcription–translation assays, however, transcription–translation assays in other important pathogens including Staphylococcus aureus and Streptococcus pneumoniae have been described (Murray et al., 2001; Dandliker et al., 2003). Pseudomonas aeruginosa is an important and difficult-to-treat Gram-negative pathogen. In a drug discovery program, to de-risk any potential species specificity of novel inhibitors, we developed and optimized a robust method for the preparation of S30 extract from P. aeruginosa strain PAO1. Further, a P. aeruginosa transcription–translation assay using a firefly luciferase reporter plasmid was validated and compared to an E. coli S30-based system using a wide range of antibiotics encompassing multiple classes of translation inhibitors. Results showed a similar ranking of the activities of known inhibitors, illustrative of the high degree of conservation between the transcription–translation pathways in both organisms.

► We describe a P. aeruginosa in vitro coupled transcription–translation system. ► P. aeruginosa and E. coli assays showed similar IC50s for translation inhibitors. ► P. aeruginosa and E. coli efflux limited cell activity of translation inhibitors. ► This assay is expected to be of use for developing new drugs for P. aeruginosa.