Identifying the Target Protein of an Antipyocyanin Compound in Pseudomonas aeruginosa Using Photoaffinity Labeling

Pseudomonas aeruginosa is an opportunistic Gram‐negative bacterium affecting those with weakened immune systems including burn victims, surgical implant patients and those with cystic fibrosis. Due to the rise in antibiotic resistance, our lab has developed an antivirulence approach to combat this pathogen. The current, and increasingly less effective, method is the antimicrobial approach that either kills the bacteria or prevents bacterial growth. An antivirulence strategy deactivates pathogenicity, here through the inhibition of redox‐active pyocyanin, a key virulence factor produced by the P. aeruginosa , which then allows the host's immune system to clear the infection on its own. We have developed a small molecule that disrupts production of pyocyanin through an unknown mechanism. Our primary objective is to identify the molecular target with a photoaffinity labeling (PAL) approach by incorporating a photoreactive diazirine ring on our inhibitor as well as a bioorthogonal reactive group, which is helpful for protein purification. We have successfully synthesized and characterized a key intermediate and will present our progress toward the target compound. PAL is a promising approach that has been successfully used to determine protein targets through the covalent bond formed upon irradiation with UV light in recent identification studies. By using affinity chromatography and proteomics we will to identify candidates for the molecular target that can be confirmed in further studies. We ultimately aim to characterize additional processes that control pyocyanin production. This information could provide new targets for future antivirulence therapeutics to combat this threatening pathogen. Support or Funding Information This research is funded by San Jose State University and CSUPERB. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .