Title

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

Authors

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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