Pseudomonas aeruginosa PHOSPHORYLCHOLINE PHOSPHATASE CONTAINS TWO SITES FOR QUATERNAY AMMONIUM

OTERO, LH; BEASSONI, PR; BOETSCH, C; DOMENECH, CE

Tucuman

Congreso; XLV Reunión Anual de la SAIB; 2009

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Pseudomonas aeruginosa phosphorylcholine phosphatase (PchP)catalyzes the hydrolysis of phosphocholine to choline and inorganicphosphate (Pi). Phosphocholine is produced after hemolyticphospholipase C (PlcH) acts upon phosphatidylcholine orsphingomyelin. Hence, PlcH and PchP are involved in thepathogenesis of P. aeruginosa. PchP belongs to the HADsuperfamily as it contains, three conserved sequences motifs namedI, II, and III that in mature PchP are 31DMDNT35, 166S, and242K/261GDTPDSD267, respectively. The enzyme activity is dependenton the presence of various divalent cations but, up to now, wefocused our attention on Mg2+, Zn2+ and Cu2+. This ions act as Lewisacids stabilizing an octahedral complex with different oxygen atomscontributed by 31D, 33D, 262D, two water molecules and an O of thephosphate moiety. With large differences in enzyme activity, Zn2+and Cu2+ are better activators than Mg2+. Kinetic experimentsperformed in wild type and site directed mutants (42E, 43E, 82YYY84)with phosphocholine as substrate plus inhibition by ammoniumquaternary compounds with p-NPP as substrate led us to proposethat PchP contains two different sites for the interaction with theammonium quaternary moiety of different compounds. Theseresults can probably be the starting point for designing new drugs toavoid the action of P. aeruginosa through the action of PlcH andPchP.