Quorum Sensing Signals Form Complexes with Ag⁺ and Cu²⁺ Cations

Abstract

Quorum sensing (QS) regulates important bacterial behaviors such as virulent protein production and biofilm formation. QS requires that molecular signals are exchanged between cells, extracellularly, where environmental conditions influence signal stability. In this work, we present a novel complexation between metal cations (Ag and Cu) and a QS autoinducer signal, N-hexanoyl- L-homoserine lactone (HHL). The molecular interactions were investigated using mass spectrometery, attenuated total reflectance-Fourier transform infrared spectroscopy, and computational simulations. Results show that HHL forms predominantly 1:1 complexes with Ag ( K = 3.41 × 10 M) or Cu ( K = 1.40 × 10 M), with the coordination chemistry occurring on the oxygen moieties. In vivo experiments with Chromobacterium violaceum CV026 show that sublethal concentrations of Ag and Cu decreased HHL-regulated QS activity. Furthermore, when Ag was preincubated with HHL, Ag toxicity to CV026 decreased by an order of magnitude, suggesting HHL:metal complexes alter the bioavailability of the individual constituents.

An In Vitro Study on the Application of Silver-Doped Platelet-Rich Plasma in the Prevention of Post-Implant-Associated Infections

“…For C. albicans, PRP-L and PRP-B demonstrated significant inhibitory activity (p < 0.0001), although lower than AMB. In this context, we hypothesize that the observed outcome may stem from the ability of silver ions to concurrently impact both cell viability and the quorum sensing signaling crucial for biofilm development, as indicated by previous research [73,[75][76][77][78][79][80]. These findings underscore the potential of PRP enriched with silver as an effective antibiofilm agent, warranting further exploration in clinical settings.…”

Biogenic Cyanide Production Promotes Dissolution of Gold Nanoparticles in Soil

“…Furthermore, the presence of other cyanide-metabolizing organisms − or quorum-quenching enzymes , could decrease the overall CN concentrations. There are also other metabolites, such as siderophores , and quorum sensing signals, , which can complex metal ions, potentially contributing to metal NP dissolution. These could be interesting topics for further dissolution studies.…”