The Pseudomonas aeruginosa PAO1 Two-Component Regulator CarSR Regulates Calcium Homeostasis and Calcium-Induced Virulence Factor Production through Its Regulatory Targets CarO and CarP

Abstract

Pseudomonas aeruginosa is an opportunistic human pathogen that causes severe, life-threatening infections in patients with cystic fibrosis (CF), endocarditis, wounds, or artificial implants. During CF pulmonary infections, P. aeruginosa often encounters environments where the levels of calcium (Ca 2؉ ) are elevated. Previously, we showed that P. aeruginosa responds to externally added Ca 2؉ through enhanced biofilm formation, increased production of several secreted virulence factors, and by developing a transient increase in the intracellular Ca 2؉ level, followed by its removal to the basal submicromolar level. However, the molecular mechanisms responsible for regulating Ca . In addition, a mutation in carP had a pleotropic effect in a Ca 2؉ -dependent manner, altering swarming motility, pyocyanin production, and tobramycin sensitivity. Overall, the results indicate that the two-component system CarSR is responsible for sensing high levels of external Ca 2؉ and responding through its regulatory targets that modulate Ca 2؉ homeostasis, surface-associated motility, and the production of the virulence factor pyocyanin. P seudomonas aeruginosa, a natural inhabitant of soil and water, is able to infect a variety of hosts, including plants and humans. In humans, it causes severe acute and chronic infections by colonizing respiratory and urinary tracts and burned or wounded epithelia, cornea, and muscles (1-3). The versatility of P. aeruginosa pathogenicity is associated with diverse metabolic capabilities, multiple mechanisms of resistance, a large repertoire of virulence factors, and adaptability, due in part to the tightly coordinated regulation of gene expression. A large portion of the P. aeruginosa PAO1 genome, approximately 9.4%, encodes transcriptional regulators (4, 5), including two-component regulators: 89 response regulators, 55 sensor kinases, and 14 sensorresponse regulator hybrids (2). The regulatory targets for most of these regulatory systems are unknown. IMPORTANCE During infectious disease,Calcium plays an important signaling role in both eukaryotic and prokaryotic cells. In prokaryotes, Ca 2ϩ is an essential nutrient, since it is a necessary cofactor for many enzymes. However, Ca 2ϩ can be toxic to cells at high concentrations; therefore, bacteria maintain a low-submicromolar intracellular concentration of Ca 2ϩ (6). P. aeruginosa may encounter environments where

Ca 2+ -Induced Two-Component System CvsSR Regulates the Type III Secretion System and the Extracytoplasmic Function Sigma Factor AlgU in Pseudomonas syringae pv. tomato DC3000

“…CarSR in Vibrio cholerae is induced by Ca 2ϩ and negatively regulates biofilm formation and exopolysaccharide production (31). In P. aeruginosa PAO1, the TCS orthologous to CvsSR, BqsSR, is also induced by Ca 2ϩ and regulates the cytosolic Ca 2ϩ concentration (38). However, to our knowledge, CvsSR is the first Ca 2ϩ -induced TCS characterized in a hemibiotrophic plant-pathogenic bacteria.…”

“…The TCS orthologous to CvsSR in Pseudomonas aeruginosa is induced by Ca 2ϩ (38). To test for induction of cvsS and cvsR by Ca 2ϩ , we designed a luciferase promoter gene construct that included 400 bp upstream of PSPTO_3383 (P cvsSR ), which included a previously mapped transcriptional start site for PSPTO_3383, and introduced it into WT, ΔcvsS, and ΔcvsR strains of P. syringae pv.…”

“…The orthologous TCS, BqsSR, in P. aeruginosa PAO1 positively regulates biofilm dispersal when P. aeruginosa PAO1 is grown in LB (62). However, when grown on BM2 agar supplemented with 10 mM CaCl 2 , swarming motility was not reduced upon deletion of bqsSR (38). As such, while each assay was performed under different conditions, it appears that BqsSR regulates biofilm lifestyle and swarming motility in a sympathetic way in P. aeruginosa PAO1.…”

Production of Dry Extract Lipase from Pseudomonas Aeruginosa by the Submerged Fermentation Method in Palm Oil Mill Effluent

“…The highest activity of 0.813 U/ml was obtained from 6 mM CaCl2.2H2O (Figure 3). Calcium is an essential element in cell signalling and is required as a cofactor for many enzymes (Guragain et al, 2016). However, a high concentration of calcium ions could be toxic to the cells and decrease growth (Guragain et al, 2016).…”

“…Calcium is an essential element in cell signalling and is required as a cofactor for many enzymes (Guragain et al, 2016). However, a high concentration of calcium ions could be toxic to the cells and decrease growth (Guragain et al, 2016). Other research conducted by Vasiee et al (2016) reported that optimal enzyme production conditions from Bacillus cereus the Submerged Fermentation Method in Palm Oil Mill Effluent incubated at 37C for 48 h were achieved with 24.23 mM MgCl2 together with a coriander seed extract (CSE)/yeast extract ratio of 16.9 (m/m) and a concentration of 2.37 g/L of olive oil.…”