Purified E255L mutant SERCA1a and purified PfATP6 are sensitive to SERCA-type inhibitors but insensitive to artemisinins.
The 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 either 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 2,5-di(tert-butyl)-1,4-benzohydroquinone than rabbit SERCA1 but retained higher sensitivity to cyclopiazonic acid, another type of SERCA1 inhibitor. Although 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.
Commissariat à l'Energie Atomique, Institut de Biologie et de Technologies de Saclay, SB2SM, France.
Delphine
D
Cardi
Alexandre
A
Pozza
Bertrand
B
Arnou
Estelle
E
Marchal
Johannes D
JD
Clausen
Jens Peter
JP
Andersen
Sanjeev
S
Krishna
Jesper V
JV
Møller
Marc
M
le Maire
Christine
C
Jaxel
D000818:Animals; D000962:Antimalarials; D037621:Artemisinins / Q000494:pharmacology*; D019556:COS Cells; D000252:Calcium-Transporting ATPases / Q000187:drug effects*; D002522:Chlorocebus aethiops; D004791:Enzyme Inhibitors / Q000494:pharmacology; D050505:Mutant Proteins; D020125:Mutation, Missense; D011817:Rabbits; D012441:Saccharomyces cerevisiae; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors* / Q000187:drug effects*
D000962:Antimalarials; D037621:Artemisinins; D004791:Enzyme Inhibitors; D050505:Mutant Proteins; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases