RpoN Modulates Carbapenem Tolerance in Pseudomonas aeruginosa through Pseudomonas Quinolone Signal and PqsE

Abstract

bThe ability of Pseudomonas aeruginosa to rapidly modulate its response to antibiotic stress and persist in the presence of antibiotics is closely associated with the process of cell-to-cell signaling. The alternative sigma factor RpoN ( 54 ) is involved in the regulation of quorum sensing (QS) and plays an important role in the survival of stationary-phase cells in the presence of carbapenems. Here, we demonstrate that a ⌬rpoN mutant grown in nutrient-rich medium has increased expression of pqsA, pqsH, and pqsR throughout growth, resulting in the increased production of the Pseudomonas quinolone signal (PQS). The link between pqsA and its role in carbapenem tolerance was studied using a ⌬rpoN ⌬pqsA mutant, in which the carbapenem-tolerant phenotype of the ⌬rpoN mutant was abolished. In addition, we demonstrate that another mechanism leading to carbapenem tolerance in the ⌬rpoN mutant is mediated through pqsE. Exogenously supplied PQS abolished the biapenem-sensitive phenotype of the ⌬rpoN ⌬pqsA mutant, and overexpression of pqsE failed to alter the susceptibility of the ⌬rpoN ⌬pqsA mutant to biapenem. The mutations in the ⌬rpoN ⌬rhlR mutant and the ⌬rpoN ⌬pqsH mutant led to susceptibility to biapenem. Comparison of the changes in the expression of the genes involved in QS in wild-type PAO1 with their expression in the ⌬rpoN mutant and the ⌬rpoN mutant-derived strains demonstrated the regulatory effect of RpoN on the transcript levels of rhlR, vqsR, and rpoS. The findings of this study demonstrate that RpoN negatively regulates the expression of PQS in nutrient-rich medium and provide evidence that RpoN interacts with pqsA, pqsE, pqsH, and rhlR in response to antibiotic stress.

Mutational Evolution of Pseudomonas aeruginosa Resistance to Ribosome-Targeting Antibiotics

“…It has also been suggested that the Sec pathway could be involved in the translocation of components of multidrug efflux pumps across the bacterial membranes ( Yoneyama et al, 2010 ; Akiba et al, 2013 ; Chaudhary et al, 2015 ), but it is unclear how changes in this translocation could increase resistance in the selected mutants. Tigecycline increased resistance may also come about through modifications of the σ 54 RpoN factor that has been found to modulate P. aeruginosa virulence ( Kazmierczak et al, 2005 ), bacterial tolerance to carbapenems ( Viducic et al, 2016 ), susceptibility to quinolones ( Viducic et al, 2007 ) and survival in the presence of tobramycin ( Viducic et al, 2017 ). Both the Sec pathway and RpoN have been proposed as excellent targets in the search of novel antibiotics ( Jin et al, 2016 ; Lloyd et al, 2017 ).…”

Dissemination of Genetic Acquisition/Loss Provides a Variety of Quorum Sensing Regulatory Properties in Pseudoalteromonas

“…The results in Supplementary Figure S4 A showed that T1lg65 and T1lg88 respectively exhibit the strongest and the weakest QS-dependent colorization of A136, and T1lg24 has colorization comparable to that of T1lg65. Subsequently, two important regulator genes, luxO and rpoN, respectively considered as positive and negative regulator genes in Vibrio and Pseudomonas [ 28 , 29 , 30 , 31 , 32 ], were chosen for analysis of relative expression level in these three Pseudoalteromonas isolates. Supplementary Figure S4B and Supplementary Figure S4C showed that the relative expression of both luxO and rpoN in three isolates is obviously different.…”

Spatially dependent alkyl quinolone signaling responses to antibiotics in Pseudomonas aeruginosa swarms

“…Because previous reports have shown various roles for PQS, namely as a stress response, for planktonic P. aeruginosa cells exposed to antimicrobials (22,26,(38)(39)(40), we were interested to explore how AQs mediate P. aeruginosa behavior in motile, prebiofilm swarm communities. Additionally, the CRM chemical profile of P. aeruginosa swarms provided evidence that tobramycin exposure cues aspects of PQS production or regulation that carbenicillin does not (Fig.…”