A novel protein phosphatase 2A (PP2A) is involved in the transformation of human protozoan parasite Trypanosoma cruzi

Author:

GONZÁLEZ Jorge1,CORNEJO Alberto1,SANTOS Marcia R. M.2,CORDERO Esteban M.2,GUTIÉRREZ Bessy1,PORCILE Patricio1,MORTARA Renato A.2,SAGUA Hernán1,da SILVEIRA José Franco2,ARAYA Jorge E.1

Affiliation:

1. Parasitology Unit, Department of Medical Technology, University of Antofagasta, Antofagasta, PO Box 170, Chile

2. Department of Microbiology, Immunology and Parasitology, UNIFESP, EPM, Rua Botucatu 862, CEP 04023-062, São Paulo, SP, Brazil

Abstract

Here we provide evidence for a critical role of PP2As (protein phosphatase 2As) in the transformation of Trypanosoma cruzi. In axenic medium at pH 5.0, trypomastigotes rapidly transform into amastigotes, a process blocked by okadaic acid, a potent PP2A inhibitor, at concentrations as low as 0.1 μM. 1-Norokadaone, an inactive okadaic acid analogue, did not affect the transformation. Electron microscopy studies indicated that okadaic acid-treated trypomastigotes had not undergone ultrastructural modifications, reinforcing the idea that PP2A inhibits transformation. Using a microcystin–Sepharose affinity column we purified the native T. cruzi PP2A. The enzyme displayed activity against 32P-labelled phosphorylase a that was inhibited in a dose-dependent manner by okadaic acid. The protein was also submitted to MS and, from the peptides obtained, degenerate primers were used to clone a novel T. cruzi PP2A enzyme by PCR. The isolated gene encodes a protein of 303 amino acids, termed TcPP2A, which displayed a high degree of homology (86%) with the catalytic subunit of Trypanosoma brucei PP2A. Northern-blot analysis revealed the presence of a major 2.1-kb mRNA hybridizing in all T. cruzi developmental stages. Southern-blot analysis suggested that the TcPP2A gene is present in low copy number in the T. cruzi genome. These results are consistent with the mapping of PP2A genes in two chromosomal bands by pulsed-field gel electrophoresis and chromoblot hybridization. Our studies suggest that in T. cruzi PP2A is important for the complete transformation of trypomastigotes into amastigotes during the life cycle of this protozoan parasite.

Publisher

Portland Press Ltd.

Subject

Cell Biology,Molecular Biology,Biochemistry

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