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.