COMPARTMENTALIZED cAMP-DEPENDENT SIGNALING IN T. cruzi BY TWO DIFFERENT PHOSPHODIESTERASES

SCHOIJET, ALEJANDRA C.; TORRES, HÉCTOR N.; FLAWIÁ, MIRTHA M.; ALONSO, GUILLERMO D.

Pinamar, Argentina.

Congreso; X Congress of the Pan-American Association for Biochemistry and Molecular Biology (PABMB), XLI Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology (SAIB) and the XX Annual Meeting of the Argentine Society for Neurochemistry (SAN; 2005

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Cyclic nucleotide-specific phosphodiesterases (PDEs) are key regulators of cAMP signaling pathways by controlling the spatial and temporal levels of intracellular cAMP. It has been proposed that compartmentalization of cAMP related enzymes is important for the regulation and specificity of cAMP signaling. In the present work, we report the identification of two novel phosphodiesterases form T. cruzi, TcPDE4 and TcPDE-D. Both were able to complement a heat-shock-sensitive yeast mutant deficient in phosphodiesterase genes. TcPDE4 presents three conserved domains, FYVE, phosphohydrolase and PDEaseI, shows the inhibition profile characteristic for PDE4 subfamily and is specific for cAMP with an intermediate Km value of about 20mM. This enzyme remained associated to membrane structures in recombinant yeast cells and confocal laser scanning microscopy of T. cruzi epimastigotes indicates that TcPDE4 seems to be located in endosome-like vesicles, according to the presence of its FYVE domain. On the other hand, TcPDE-D doesn’t present other functional domains besides the catalytic domain. Finally, subcellular fractionation of T. cruzi epimastigotes followed by Western blot assays revealed that this enzyme is located mainly in the citoplasmatic fraction.