Ca2+ transport into an intracellular acidic compartment of Candida parapsilosis

In this report, we study Ca2+ transport in permeabilized Candida parapsilos is spheroplasts prepared by a new technique using lyticase, An intracellula r non-mitochondrial Ca2+ uptake pathway, insensitive to orthovanadate and s ensitive to the V-H+-ATPase inhibitor bafilomycin A(1), nigericin and carbo nyl cyanide p-trifluoromethoxyphenylhydrazone was characterized, Acidificat ion of the compartment in which Ca2+ accumulated was followed using the flu orescent dye acridine orange. Acidification was stimulated by the Ca2+ chel ator EGTA and inhibited by Ca2+ These results, when added to the observatio n that Ca2+ induces alkalization of a cellular compartment, provide evidenc e for the presence of a Ca2+/nH(+) antiporter in the acid compartment membr ane. Interestingly, like in acidocalcisomes of trypanosomatids, the antioxi dant 3,5-dibutyl-4-hydroxytoluene inhibits the V-H+-ATPase, In addition, th e antifungal agent ketoconazole promoted a fast alkalization of the acidic compartment, Ketoconazole effects mere dose-dependent and occurred in a con centration range close to that attained in the plasma of patients treated w ith this drug. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.