Cytosolic Ca2+ homeostasis is a constitutive function of the V-ATPase in Saccharomyces cerevisiae.
The vacuole is the major site of intracellular Ca(2+) storage in yeast and functions to maintain cytosolic Ca(2+) levels within a narrow physiological range via a Ca(2+) pump (Pmc1p) and a H(+)/Ca(2+) antiporter (Vcx1p) driven by the vacuolar H(+)-ATPase (V-ATPase). We examined the function of the V-ATPase in cytosolic Ca(2+) homeostasis by comparing responses to a brief Ca(2+) challenge of a V-ATPase mutant (vma2Delta) and wild-type cells treated with the V-ATPase inhibitor concanamycin A. The kinetics of the Ca(2+) response were determined using transgenic aequorin as an in vivo cytosolic Ca(2+) reporter system. In wild-type cells, the V-ATPase-driven Vcx1p was chiefly responsible for restoring cytosolic Ca(2+) concentrations after a brief pulse. In cells lacking V-ATPase activity, brief exposure to elevated Ca(2+) compromised viability, even when there was little change in the final cytosolic Ca(2+) concentration. vma2Delta cells were more efficient at restoring cytosolic [Ca(2+)] after a pulse than concanamycin-treated wild-type cells, suggesting long term loss of V-ATPase triggers compensatory mechanisms. This compensation was dependent on calcineurin, and was mediated primarily by Pmc1p.
Forster
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Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Syracuse, New York 13210, USA.
Kane
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PM
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D019703:Calcineurin / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D003600:Cytosol / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005656:Fungal Proteins / Q000378:metabolism; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D018942:Macrolides; D009183:Mycotoxins; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D025262:Vacuolar Proton-Translocating ATPases
D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D018942:Macrolides; D009183:Mycotoxins; D011994:Recombinant Proteins; C093771:Vex1 protein, Pythium vexans; C036978:concanamycin A; D019703:Calcineurin; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; D002118:Calcium