J Biol Chem. April 3, 2013;
Purified E255L mutant SERCA1a and purified PFATP6 are sensitive to SERCA-type inhibitors but insensitive to artemisinins.
AbstractThe antimalarial drugs artemisinins have been described as inhibiting Ca(2+)-ATPase activity of PfATP6 (Plasmodium falciparum ATP6), after expression in Xenopus oocytes. Mutation of an amino acid residue in mammalian SERCA1 (Glu 255) to the equivalent one predicted in PfATP6 (Leu) was reported to induce sensitivity to artemisinin in the oocyte system. However, in the present experiments we found that artemisinin did not inhibit mammalian SERCA1a E255L both when expressed in COS cells or after purification of the mutant expressed in Saccharomyces cerevisiae. Moreover, we found that PfATP6 after expression and purification from S. cerevisiae was insensitive to artemisinin and significantly less sensitive to thapsigargin and BHQ than rabbit SERCA1, but retained higher sensitivity to CPA, another type of SERCA1 inhibitor. While mammalian SERCA and purified PfATP6 appear to have different pharmacological profiles, their insensitivity to artemisinins suggests that the mechanism of action of this class of drugs on the calcium metabolism in the intact cell is complex and cannot be ascribed to direct inhibition of PfATP6. Furthermore, the successful purification of PfATP6 affords the opportunity to develop new antimalarials by screening for inhibitors against PfATP6.
Pubmed Id: 20530490Article link: J Biol Chem.