Modulation of antibiotic sensitivity and biofilm formation in Pseudomonas aeruginosa by interspecies signal analogues

Abstract

Pseudomonas aeruginosa , a significant opportunistic pathogen, can participate in inter-species communication through signaling by cis -2-unsaturated fatty acids of the diffusible signal factor (DSF) family. Sensing these signals leads to altered biofilm formation and increased tolerance to various antibiotics, and requires the histidine kinase PA1396. Here, we show that the membrane-associated sensory input domain of PA1396 has five transmembrane helices, two of which are required for DSF sensing. DSF binding is associated with enhanced auto-phosphorylation of PA1396 incorporated into liposomes. Further, we examined the ability of synthetic DSF analogues to modulate or inhibit PA1396 activity. Several of these analogues block the ability of DSF to trigger auto-phosphorylation and gene expression, whereas others act as inverse agonists reducing biofilm formation and antibiotic tolerance, both in vitro and in murine infection models. These analogues may thus represent lead compounds to develop novel adjuvants improving the efficacy of existing antibiotics.

Quorum-Sensing Regulation of Antimicrobial Resistance in Bacteria

“…For example, in P. aeruginosa, the QS system has two signaling systems: lasl/lasR and rhlI/rhlI. The lasl/rhlI and lasR and rhlR genes encode different signal molecule synthetases and signal molecule receptors, respectively [77,78]. Signal molecules increase in secretion as the density of bacteria increases.…”

2-Heptylcyclopropane-1-Carboxylic Acid Disperses and Inhibits Bacterial Biofilms

“…In one dispersal study, Rahmani-Badi et al (2015b) have identified protein transcription changes occurring in P. aeruginosa upon stimulation with C2DA, identifying a cluster of genes implicated in sensing and responding to fatty-acid signals, including regulation of pathogenicity factor (rpf) proteins. It has also been shown that the histidine kinase PA1396 in P. aeruginosa is a major factor in DSF function; certain DSF analogs are able to block the ability of PA1396 to autophosphorylate, which subsequently reduces biofilm formation and antibiotic tolerance both in vitro and in vivo ( An et al, 2019 ). Previous research has also demonstrated that C2DA increased membrane permeability of P. aeruginosa and S. aureus ( Masters et al, 2016 ), which may occur by substitution of membrane phospholipids by fatty acid or by stimulating proton-motive force at the membrane ( Meylan et al, 2017 ).…”

Controlled spatial organization of bacterial clusters reveals cell filamentation is vital forXylella fastidiosabiofilm formation

“…If indeed potential cell-cell communication via quorum sensing mediates the formation of filamentous cells 7,33,34 , we reasoned that variances in distance between Au disks should affect this process. Following this idea, the formation of filamentous cells was monitored via fluorescence imaging of cells clusters separated over various distances.…”

“…Bacteria have evolved diverse surface adhesion mechanisms to enable biofilm formation on biotic and abiotic substrates in a variety of natural, medical, and industrial settings [1][2][3] . The virulence of pathogenic bacteria strongly depends on their capability to attach to biotic surfaces and form multicellular assemblies [4][5][6][7][8] . Such pathogenic biofilms are highly resistant to diverse antimicrobial compounds due to their encapsulation within a matrix of hydrated extracellular polymeric substances (EPS) 7,9 .…”

“…The virulence of pathogenic bacteria strongly depends on their capability to attach to biotic surfaces and form multicellular assemblies [4][5][6][7][8] . Such pathogenic biofilms are highly resistant to diverse antimicrobial compounds due to their encapsulation within a matrix of hydrated extracellular polymeric substances (EPS) 7,9 . A better understanding of the mechanisms of bacterial adhesion and biofilm formation is thus vital to reveal potential vulnerabilities that can lead to their prevention and disruption 2,10 .…”