Publication Date:
2013-09-24
Description:
The plasma membrane protein CaRch1p of Candida albicans , homologous to the human solute carrier protein SLC10A7, is involved in the regulation of calcium homeostasis. C. albicans cells lacking CaRCH1 are hypersensitive to high extracellular Ca 2+ concentrations and show increased tolerance to ketoconazole (KCZ). We assume a higher basal Ca 2+ influx in the rch1/rch1 mutant strain at low extracellular Ca 2+ concentrations which is not detrimental to C. albicans cells but may be sufficient to activate calcineurin, finally resulting in an increased tolerance to KCZ. However, at 8 µg/ml KCZ plus 3 mM Ca 2+ the rch1/rch1 mutant and the wild type strains showed identical growth. By further increasing the Ca 2+ concentration to 30 mM this phenotype completely reversed and the rch1/rch1 mutant strain became extremely sensitive to 8 µg/ml KCZ, probably due to synergistic toxic effects of Ca 2+ and KCZ under these conditions. Furthermore, we aimed to clarify if CaRch1p interacts with the Cch1p component of the voltage-gated calcium influx channel Cch1p/Mid1p in C. albicans cells. As disruption of the two alleles of CCH1 in the rch1 / rch1 mutant strain did not alter its hypersensitivity to high extracellular Ca 2+ , and, as this phenotype was completely abolished by low amounts of Mg 2+ in the rch1/rch1 mutant as well as in the cch1/cch1 rch1/rch1 double mutant, we conclude that CaRch1p is a functional component of the low-affinity calcium uptake system (LACS) system and does not functionally interact with Cch1p. This article is protected by copyright. All rights reserved.
Print ISSN:
0749-503X
Electronic ISSN:
1097-0061
Topics:
Biology
