Beyond iron: metal-binding activity of the Pseudomonas quinolone signal-motif

The Pseudomonas quinolone signal (PQS) is an important quorum sensing signal controlling virulence of the human pathogen Pseudomonas aeruginosa. PQS also exhibits multiple additional biological functions for P. aeruginosa, including the trapping of ferric iron. The PQS-motif has proven as privileged structure with great potential which is why we here explored the synthesis of two different types of crosslinked dimeric PQS-motifs as potential iron chelators. These compounds indeed chelated ferric iron and produced colorful and fluorescent complexes also with other metal ions. Inspired by these results, we revisited the metal ion binding capabilities of the natural product PQS and were able to detect further metal complexes beyond ferric iron and confirm the complex stoichiometry by mass spectrometry.

Automated summary

The Pseudomonas quinolone signal (PQS) plays a vital role in controlling the pathogenicity of Pseudomonas aeruginosa. PQS exhibits diverse biological functions, including iron trapping. In this study, we synthesized two types of crosslinked dimeric PQS motifs as potential iron chelators and successfully chelated ferric iron, forming colorful and fluorescent complexes with other metal ions. Furthermore, we explored the metal ion binding capabilities of natural PQS and identified additional metal complexes beyond ferric iron, confirming the complex stoichiometry using mass spectrometry.