A novel extracellular phospholipase C of Pseudomonas aeruginosa is required for phospholipid chemotaxis

Abstract

SummaryPseudomonas aeruginosa and other bacterial pathogens express one or more homologous extracellular phospholipases C (PLC) that are secreted through the inner membrane via the twin arginine translocase (TAT) pathway. Analysis of TAT mutants of P. aeruginosa uncovered a previously unidentified extracellular PLC that is secreted via the Sec pathway (PlcB). Whereas all presently known PLCs of P. aeruginosa (PlcH, PlcN and PlcB) hydrolyse phosphatidylcholine (PC), only PlcB is active on phosphatidylethanolamine (PE). plcB candidates were identified based on deductions made from bioinformatics data and extant DNA microarray data. Among these candidates, a gene (PA0026) required for the expression of an extracellular PE-PLC was identified. The protein encoded by PA0026 has limited, but significant similarity, over a short region ( ~ 60aa of 328), to a class of zinc-dependent prokaryotic PLCs. A conserved His residue of PlcB (His216) that is required for coordinate binding of zinc in this class of PLCs was mutated. Analysis of this mutant established that the protein encoded by PA0026 is PlcB. Three independent recently published reports indicate that homoserine lactone-mediated quorum sensing regulates the expression of PA0026 (i.e. plcB ). PlcB, but not PlcH or PlcN, is required for directed twitching motility up a gradient of certain kinds of phospholipids. This response shows specificity for the fatty acid moiety of the phospholipid.

Molecular Identification and Virulence Factors of Pseudomonas Aeruginosa Strains Isolated from Animal Products

“…This alginate prevalence indicates that isolated strains of animal products are involved in the formation of biofilms as alginates have been widely regarded as the major exopolysaccharides of the biofilm matrix [24,25]. The prevalences of plcH (71.0%) gene showed that strains isolated were able of secreting hemolytic exoenzyme and phospholipase C and thus strains could be involved in pulmonary infections [26,27]. Our results obtained in this study correlate with those proved by Bradbury et al [28] who proved that P. aeruginosa isolated from nosocomial infections were found to have an increased prevalence of virulence genes.…”

Pouring Salt on a Wound: Pseudomonas aeruginosa Virulence Factors Alter Na+ and Cl- Flux in the Lung

“…Protease IV also degrades surfactant proteins A, B, and D, which are important for surface tension and innate immunity (35). The phospholipases PlcB, PlcH, and PlcN target the mucus layer and cell membrane, facilitating bacterial transit through the mucus layer and liberating nutrients exploited by the bacteria (36)(37)(38). Furthermore, PlcH has been shown to suppress the neutrophil respiratory burst, which may also facilitate P. aeruginosa survival (39).…”

Pseudomonas aeruginosa Twitching Motility-Mediated Chemotaxis towards Phospholipids and Fatty Acids: Specificity and Metabolic Requirements

“…Twitching motility chemotaxis assays were performed as previously described (3,13). In brief, twitching assay plates containing buffered agar (10 mM Tris, pH 7.6; 8 mM MgSO 4 ; 1 mM NaPO 4 , pH 7.6; and 1.5% agar) were allowed to dry overnight at 25°C before 4-l spots of 10 mg/ml PE, 20 mg/ml LCFA, or 0.72 mg/ml BALF were placed on the agar …”