Sodium antiporters of Pseudomonas aeruginosa in challenging conditions: effects on growth, biofilm formation, and swarming motility

Abstract

Background: Pseudomonas aeruginosa is a bacterial pathogen that can cause grave and sometimes chronic infections in patients with weakened immune systems and cystic fibrosis. It is expected that sodium/proton transporters in the cellular membrane are crucial for the organism's survival and growth under certain conditions, since many cellular processes rely on the maintenance of Na + and H + transmembrane gradients. Results: This study focused on the role of the primary and secondary proton and/or sodium pumps Mrp, Nuo, NhaB, NhaP, and NQR for growth, biofilm formation, and swarming motility in P. aeruginosa. Using mutants with gene deletions, we investigated the impact of each sodium pump's absence on the overall growth, biofilm formation, motility, and weak acid tolerance of the organism. We found that the absence of some, but not all, of the sodium pumps have a deleterious effect on the different phenotypes of P. aeruginosa. Conclusion: The absence of the Mrp sodium/proton antiporter was clearly important in the organism's ability to survive and function in environments of higher pH and sodium concentrations, while the absence of Complex I, which is encoded by the nuo genes, had some consistent impact on the organism's growth regardless of the pH and sodium concentration of the environment.

Na+ homeostasis in Acinetobacter baumannii is facilitated via the activity of the Mrp antiporter

“…Another explanation for the observed phenotypes might be a continuous Na + influx resulting in a self-detoxification over time that causes depletion of the cellular ATP content, motility inhibition and decreased viability. This pleiotropic has been reported before in an mrp mutant of P. aeruginosa that is also unable to move across surfaces (Schubiger et al, 2020).…”

“…To guarantee an internal pH that maintain enzymatic functions bacteria adjust their internal pH in a narrow range of 7.4–7.8 (Padan et al ., 2005). Therefore, under alkaline external conditions bacteria actively acidify their cytoplasm via Na + /H + antiporter by H + uptake coupled to Na + export (Hamamoto et al ., 1994; Kosono et al ., 1999; Padan et al ., 2005; Schubiger et al ., 2020). Thereby, two birds are killed with one stone: pH regulation and generation of a sodium motive force.…”

“…This pleiotropic has been reported before in an mrp mutant of P . aeruginosa that is also unable to move across surfaces (Schubiger et al ., 2020).…”

Occurrence, antimicrobial susceptibility, and pathogenic factors of Pseudomonas aeruginosa in canine clinical samples

“…Biofilm production was assessed by microtiter plate assay, as previously described [ 20 , 21 ]. P. aeruginosa cultures were inoculated into Luria Bertani (LB) broth to create a suspension with OD 595 of 0.1 and 200 μL of each isolate were then placed in triplicate into 96-well polystyrene microtiter plate.…”

Prokaryotic Na+/H+ Exchangers—Transport Mechanism and Essential Residues

“…In P. aeruginosa , four Na + /H + exchangers are present, NhaP, NhaP2, NhaB, and Mrp [ 62 , 63 , 64 ]. The deletion of the four genes encoding for these exchangers still allowed the growth of P. aeruginosa in the presence of Na + under some conditions, but always slower and to lower final cell densities than the WT strain [ 62 ].…”