Leishmania amazonensis: PKC-like protein kinase modulates the (Na++K+)ATPase activity

The present study aimed to identify the presence of protein kinase C-like (PKC-like) in Leishmania amazonensis and to elucidate its possible role in the modulation of the (Na++K+)ATPase activity. Immunoblotting experiments using antibody against a consensus sequence (Ac 543-549) of rabbit protein kinase C (PKC) revealed the presence of a protein kinase of 80 kDa in L. amazonensis. Measurements of protein kinase activity showed the presence of both (Ca2+-dependent) and (Ca2+-independent) protein kinase activity in plasma membrane and cytosol. Phorbol ester (PMA) activation of the Ca2+-dependent protein kinase stimulated the (Na++K+)ATPase activity, while activation of the Ca2+-independent protein kinase was inhibitory. Both effects of protein kinase on the (Na++K+)ATPase of the plasma membrane were lower than that observed in intact cells. PMA induced the translocation of protein kinase from cytosol to plasma membrane, indicating that the maximal effect of protein kinase on the (Na++K+)ATPase activity depends on the synergistic action of protein kinases from both plasma membrane and cytosol. This is the first demonstration of a protein kinase activated by PMA in L. amazonensis and the first evidence for a possible role in the regulation of the (Na++K+)ATPase activity in this trypanosomatid. Modulation of the (Na++K+)ATPase by protein kinase in a trypanosomatid opens up new possibilities to understand the regulation of ion homeostasis in this parasite.