A Theileria parva type 1 protein phosphatase activity.
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.
Cayla
X
X
Laboratoire de Physiologie de la Reproduction, INRA CNRS-ESA 7080, 9 Quai Saint Bernard, 75005, Paris, France.
Garcia
A
A
Baumgartner
M
M
Ozon
R
R
Langsley
G
G
D000818:Animals; D001402:B-Lymphocytes / Q000469:parasitology*; D002417:Cattle; D002478:Cells, Cultured; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010762:Phosphorylase a / Q000378:metabolism; D054645:Protein Phosphatase 1; D016797:Theileria parva / Q000201:enzymology*
D010762:Phosphorylase a; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1