The mechanism by which extracellular metabolites including redox mediators and quorum sensing signaling molecules, traffic through the extracellular matrix of biofilms is poorly explored. We hypothesize that functional amyloids, abundant in natural biofilms and possessing hydrophobic domains, retain these metabolites. Using surface plasmon resonance, we demonstrate that the quorum sensing (QS) molecules, 2-heptyl-3,4- dihydroxyquinoline (PQS) and N-(3- oxododecanoyl)-L-homoserine lactone (3-oxoC12-HSL), and the redox mediator pyocyanin bind with transient affinity to functional amyloids from Pseudomonas (Fap). Their high hydrophobicity predisposes them to signalamyloid interactions, but specific interactions al... More
The mechanism by which extracellular metabolites including redox mediators and quorum sensing signaling molecules, traffic through the extracellular matrix of biofilms is poorly explored. We hypothesize that functional amyloids, abundant in natural biofilms and possessing hydrophobic domains, retain these metabolites. Using surface plasmon resonance, we demonstrate that the quorum sensing (QS) molecules, 2-heptyl-3,4- dihydroxyquinoline (PQS) and N-(3- oxododecanoyl)-L-homoserine lactone (3-oxoC12-HSL), and the redox mediator pyocyanin bind with transient affinity to functional amyloids from Pseudomonas (Fap). Their high hydrophobicity predisposes them to signalamyloid interactions, but specific interactions also play a role. Transient interactions allow for rapid association and dissociation kinetics, which make the QS molecules bioavailable and at the same time secure within the extracellular matrix as a consequence of serial bindings. Retention of the QS molecules was
confirmed using P. aeruginosa PAO1 based
PQS and 3-oxo-C12-HSL reporter assays,
showing that Fap fibrils pre-treated with the
QS molecules activate the reporters even after
sequential washes. Pyocyanin retention was
validated by electrochemical analysis of
pyocyanin pre-treated Fap fibrils subjected to
the same washing process. Results suggest that
QS molecules-amyloid interactions are
probably important in turbulent environments
commonly encountered in natural habitats.