Exploring the Properties of Unilamellar Vesicle Bilayers Formed by Ionic Liquid Surfactants for Future Applications in Nanomedicine.

Two ionic liquids (ILs) with amphiphilic properties composed of 1-butyl-3-methylimidazolium dioctylsulfosuccinate (bmim-AOT) and 1-hexyl-3-methylimidazolium dioctylsulfosuccinate (hmim-AOT) form unilamellar vesicles spontaneously simply by dissolving the IL-like surfactant in water. These novel vesicles were characterized using two different and highly sensitive fluorescent probes: 6-propionyl-2-(dimethylaminonaphthalene) (PRODAN) and -4-[4-(dimethylamino)-styryl]-1-methylpyridinium iodide (HC). These fluorescent probes provide information about the physicochemical properties of the bilayer, such as micropolarity, microviscosity, and electron-donor capacity.

Putative binding mode of Escherichia coli exopolyphosphatase and polyphosphates based on a hybrid in silico/biochemical approach.

The exopolyphosphatase of Escherichia coli processively and completely hydrolyses long polyphosphate chains to ortho-phosphate. Genetic surveys, based on the analysis of single ppx(-) or ppk(-) mutants and on the double mutant, demonstrate a relationship between these genes and the survival capacity. The exopolyphosphatase belongs to the ASKHA protein superfamily, hence, its active site is well known; however, the knowledge of the way in which this enzyme binds polyP remains incomplete.

Pseudomonas aeruginosa Exopolyphosphatase Is Also a Polyphosphate: ADP Phosphotransferase.

Pseudomonas aeruginosa exopolyphosphatase (paPpx; EC 3.6.1.

Exopolyphosphatase of Pseudomonas aeruginosa is essential for the production of virulence factors, and its expression is controlled by NtrC and PhoB acting at two interspaced promoters.

The exopolyphosphatase (Ppx) of Pseudomonas aeruginosa is encoded by the PA5241 gene (ppx). Ppx catalyses the hydrolysis of inorganic polyphosphates to orthophosphate (Pi). In the present work, we identified and characterized the promoter region of ppx and its regulation under environmental stress conditions.

Phosphorylcholine Phosphatase: A Peculiar Enzyme of Pseudomonas aeruginosa.

Pseudomonas aeruginosa synthesizes phosphorylcholine phosphatase (PchP) when grown on choline, betaine, dimethylglycine or carnitine. In the presence of Mg(2+) or Zn(2+), PchP catalyzes the hydrolysis of p-nitrophenylphosphate (p-NPP) or phosphorylcholine (Pcho). The regulation of pchP gene expression is under the control of GbdR and NtrC; dimethylglycine is likely the metabolite directly involved in the induction of PchP.

Different Effects of Mg and Zn on the Two Sites for Alkylammonium Compounds in Pseudomonas aeruginosa Phosphorylcholine Phosphatase.

Pseudomonas aeruginosa phosphorylcholine phosphatase (PchP) catalyzes the hydrolysis of phosphorylcholine (Pcho), is activated by Mg(2+) or Zn(2+), and is inhibited by high concentrations of substrate. This study has shown that PchP contains two sites for alkylammonium compounds (AACs): one in the catalytic site near the metal ion-phosphoester pocket, and the other in an inhibitory site responsible for the binding of the alkylammonium moiety. The catalytic mechanism for the entry of Pcho in both sites and Zn(2+) or Mg(2+) follows a random sequential mechanism.

Site-directed mutations and kinetic studies show key residues involved in alkylammonium interactions and reveal two sites for phosphorylcholine in Pseudomonas aeruginosa phosphorylcholine phosphatase.

Pseudomonas aeruginosa phosphorylcholine phosphatase (PchP) catalyzes the hydrolysis of phosphorylcholine (Pcho) to produce choline and inorganic phosphate. PchP belongs to the haloacid dehalogenase superfamily (HAD) and possesses the three characteristic motifs of this family: motif I ((31)D and (33)D), motif II ((166)S), and motif III ((242)K, (261)G, (262)D and (267)D), which fold to form the catalytic site that binds the metal ion and the phosphate moiety of Pcho. Based on comparisons to the PHOSPHO1 and PHOSPHO2 human enzymes and the choline-binding proteins of Gram-(+) bacteria, we selected residues (42)E and (43)E and the aromatic triplet (82)YYY(84) for site-directed mutagenesis to study the interactions with Pcho and p-nitrophenylphosphate as substrates of PchP.

Choline catabolism, σ⁵⁴ factor and NtrC are required for the full expression of the Pseudomonas aeruginosa phosphorylcholine phosphatase gene.

Choline favors the pathogenesis of Pseudomonas aeruginosa because hemolytic phospholipase C and phosphorylcholine phosphatase (PchP) are synthesized as a consequence of its catabolism. The experiments performed here resulted in the identification of the factors that regulate both the catabolism of choline and the gene coding for PchP. We have also identified and characterized the promoter of the pchP gene, its transcriptional organization and the factors that affect its expression.

Crystallization and preliminary X-ray diffraction analysis of Pseudomonas aeruginosa phosphorylcholine phosphatase.

Pseudomonas aeruginosa phosphorylcholine phosphatase (PchP) catalyzes the hydrolysis of phosphorylcholine to produce choline and inorganic phosphate. Phosphorylcholine is released by the action of haemolytic phospholipase C (PlcH) on phosphatidylcholine or sphingomyelin. PchP belongs to the HAD superfamily and its activity is dependent on Mg2+, Zn2+ or Cu2+.

Transition from octahedral to tetrahedral geometry causes the activation or inhibition by Znf2+ of Pseudomonas aeruginosa phosphorylcholine phosphatase.

Pseudomonas aeruginosa phosphorylcholine phosphatase (PchP) catalyzes the hydrolysis of phosphorylcholine, which is produced by the action of hemolytic phospholipase C on phosphatidylcholine or sphyngomielin, to generate choline and inorganic phosphate. Among divalent cations, its activity is dependent on Mg(2+) or Zn(2+). Mg(2+) produced identical activation at pH 5.

Preparation and biophysical characterization of recombinant Pseudomonas aeruginosa phosphorylcholine phosphatase.

Pseudomonas aeruginosa infections constitute a widespread health problem with high economical and social impact, and the phosphorylcholine phosphatase (PchP) of this bacterium is a potential target for antimicrobial treatment. However, drug design requires high-resolution structural information and detailed biophysical knowledge not available for PchP. An obstacle in the study of PchP is that current methods for its expression and purification are suboptimal and allowed only a preliminary kinetic characterization of the enzyme.

Using a molecular model and kinetic experiments in the presence of divalent cations to study the active site and catalysis of Pseudomonas aeruginosa phosphorylcholine phosphatase.

Phosphorylcholine phosphatase (PchP) of Pseudomonas aeruginosa, a product of the PA5292 gene, catalyzes the hydrolysis of phosphocholine to choline and inorganic phosphate (Pi). Phosphocholine is produced after hemolytic phospholipase C (PlcH) acts upon phosphatidylcholine or sphingomyelin. Therefore, PlcH and PchP are involved in the pathogenesis of P.

Critical active-site residues identified by site-directed mutagenesis in Pseudomonas aeruginosa phosphorylcholine phosphatase, a new member of the haloacid dehalogenases hydrolase superfamily.

Pseudomonas aeruginosa phosphorylcholine phosphatase (PChP), the product of the PA5292 gene, is synthesized when the bacteria are grown with choline, betaine, dimethylglycine, or carnitine. In the presence of Mg(2+), PChP catalyzes the hydrolysis of both phosphorylcholine (PCh) and p-nitrophenylphosphate (p-NPP). PCh saturation curve analysis of the enzyme with or without the signal peptide indicated that the peptide was the fundamental factor responsible for decreasing the affinity of the second site of PChP for PCh, either at pH 5.

Identification, cloning, and expression of Pseudomonas aeruginosa phosphorylcholine phosphatase gene.

Pseudomonas aeruginosa phosphorylcholine phosphatase (PChP) is a periplasmic enzyme produced simultaneously with the hemolytic phospholipase C (PLc-H) when the bacteria are grown in the presence of choline, betaine, dimethylglycine or carnitine. Molecular analysis of the P. aeruginosa mutant JUF8-00, after Tn5-751 mutagenesis, revealed that the PA5292 gene in the P.