Pseudomonas aeruginosa phosphorylcholine phosphatase is a new member for the bacterial haloacid dehalogenase superfamily

BEASSONI, PR; MASSIMELLI, MJ; LISA, AT; DOMENECH, CE

Pinamar, Buenos Aires

Congreso; XLI Reunión Anual, Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2005

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

P. aeruginosa phosphorylcholine phosphatase (PChP), product of PA5292 gene, catalyses the hydrolysis of phosphorylcholine in choline and Pi. We proposed a mechanism that would explain the pulmonary infection through the coordinated action of hemolytic phospholipase C on phosphatidylcholine or sphingomyelyn, and on phosphorylcholine. Therefore, PChP is a potential target enzyme to avoid the pathogenic action of this bacterium. Based on PChP predicted secondary structure and by comparison with the crystal structure of phosphoserine phosphatase of Methanococcus janaschii (PDB: 1f5s) a three-dimensional model for PChP was built. With this model, the three conserved motifs characteristics of HAD superfamily were identified in PChP. Site-directed mutagenesis of aspartyl and treonyl residues in motif I (DXDXT) plus ligand docking simulation indicated that both aspartyl residues are essential for catalysis. The substitution of the treonyl residue by serine caused 90% depletion in the catalytic efficiency of the mutated enzyme. In addition to P. aeruginosa PChP, other homologous proteins found in P. fluorescens, P. syringae, and P. putida belong also to HAD superfamily