Article

A Theileria parva type 1 protein phosphatase activity

Laboratoire de Physiologie de la Reproduction, INRA CNRS-ESA 7080, 9 Quai Saint Bernard, 75005 Paris, France; Laboratoire de Signalisation Immuno-Parasitaire, URA CNRS 1960, Département d'Immunologie, Institut Pasteur, 25 rue du Dr Roux, 75015 Paris, France
Molecular and Biochemical Parasitology (Impact Factor: 2.73). 10/2000; DOI: 10.1016/S0166-6851(00)00266-8

ABSTRACT The protozoan parasite Theileria (spp. parva and annulata) infects bovine leukocytes and provokes a leukaemia-like disease in vivo. In this study, we have detected a type 1 serine/threonine phosphatase activity with phosphorylase a as a substrate, in protein extracts of parasites purified from infected B lymphocytes. In contrast to this type 1 activity, dose response experiments with okadaic acid (OA), a well characterised inhibitor of type 1 and 2A protein phosphatases, indicated that type 2A is the predominant activity detected in host B cells. Furthermore, consistent with polycation-specific activation of the type 2A phosphatase, protamine failed to activate the parasite-associated phosphorylase a phosphatase activity. Moreover, inhibition of phosphorylase a dephosphorylation by phospho-DARPP-32, a specific type 1 inhibitor, clearly demonstrated that a type 1 phosphatase is specifically associated with the parasite, while the type 2A is predominantly expressed in the host lymphocyte. Since an antibody against bovine catalytic protein phosphatase 1 (PP1) subunit only recognised the PP1 in B cells, but not in parasite extracts, we conclude that in parasites the PP1 activity is of parasitic origin. Intriguingly, since type 1 OA-sensitive phosphatase activity has been recently described in Plasmodium falciparum, we can conclude that these medically important parasites produce their one PP1.

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