Characterization of a novel serine/threonine protein phosphatase (PfPPJ) from the malaria parasite, Plasmodium falciparum

    Authors

    S. Dobson; V. Bracchi; D. Chakrabarti;S. Barik

    Comments

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    Abbreviated Journal Title

    Mol. Biochem. Parasitol.

    Keywords

    protein phosphatase; Plasmodium falciparum; okadaic acid; stage-specific; expression; SER-THR PHOSPHATASES; MUTATIONAL ANALYSIS; CATALYTIC SUBUNIT; DEVELOPMENTAL REGULATION; EXPRESSION; INHIBITION; IDENTIFICATION; CALCINEURIN; PHOSPHORYLATION; LOCALIZATION; Biochemistry & Molecular Biology; Parasitology

    Abstract

    A novel protein phosphatase cDNA of the PPP superfamily was identified from the malaria parasite, Plasmodium falciparum (Pf), and tentatively named PfPPJ. The predicted primary structure of the phosphatase contained all the known conserved motifs of the PPP superfamily essential for catalytic activity. The enzyme was specific for dephosphorylation of phosphoserine and phosphothreonine residues with very little activity against phosphotyrosine residues. However, the sequence at its C-terminal end was unique, and was consistent with its resistance to the classical PP2A-specific inhibitors such as okadaic acid and microcystin-LR, and the PPI-specific inhibitor, mammalian heat-stable inhibitor-2 (I-2). Even the catalytic core of PfPPJ had a sequence substantially different from the other PPPs such that PfPPJ could be placed in an apparently separate phylogenetic branch. At 294 amino acids residues, PfPPJ was one of the smallest okadaic acid-resistant PPP phosphatases known. By Northern blot analysis, the expression of the PfPPJ mRNA showed the following pattern: schizont > ring > trophozoite, which closely paralleled the expression of the protein, as determined by immunofluorescence. Together, these results suggested a parasitic stage-specific transcriptional regulation of this novel and potentially unique protozoan phosphatase. (C) 2001 Elsevier Science B.V. All rights reserved.

    Journal Title

    Molecular and Biochemical Parasitology

    Volume

    115

    Issue/Number

    1

    Publication Date

    1-1-2001

    Document Type

    Article; Proceedings Paper

    Language

    English

    First Page

    29

    Last Page

    39

    WOS Identifier

    WOS:000170128100003

    ISSN

    0166-6851

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