Calcineurin-dependent growth control in Saccharomyces cerevisiae mutants lacking PMC1, a homolog of plasma membrane Ca2+ ATPases.
Ca2+ ATPases deplete the cytosol of Ca2+ ions and are crucial to cellular Ca2+ homeostasis. The PMC1 gene of Saccharomyces cerevisiae encodes a vacuole membrane protein that is 40% identical to the plasma membrane Ca2+ ATPases (PMCAs) of mammalian cells. Mutants lacking PMC1 grow well in standard media, but sequester Ca2+ into the vacuole at 20% of the wild-type levels. pmc1 null mutants fail to grow in media containing high levels of Ca2+, suggesting a role of PMC1 in Ca2+ tolerance. The growth inhibitory effect of added Ca2+ requires activation of calcineurin, a Ca2+ and calmodulin-dependent protein phosphatase. Mutations in calcineurin A or B subunits or the inhibitory compounds FK506 and cyclosporin A restore growth of pmc1 mutants in high Ca2+ media. Also, growth is restored by recessive mutations that inactivate the high-affinity Ca(2+)-binding sites in calmodulin. This mutant calmodulin has apparently lost the ability to activate calcineurin in vivo. These results suggest that activation of calcineurin by Ca2+ and calmodulin can negatively affect yeast growth. A second Ca2+ ATPase homolog encoded by the PMR1 gene acts together with PMC1 to prevent lethal activation of calcineurin even in standard (low Ca2+) conditions. We propose that these Ca2+ ATPase homologs are essential in yeast to deplete the cytosol of Ca2+ ions which, at elevated concentrations, inhibits yeast growth through inappropriate activation of calcineurin.
Cunningham
K W
KW
Whitehead Institute, Massachusetts Institute of Technology, Cambridge 02142.
Fink
G R
GR
D000595:Amino Acid Sequence; D001483:Base Sequence; D019703:Calcineurin; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D002147:Calmodulin / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D003001:Cloning, Molecular; D016572:Cyclosporine / Q000494:pharmacology; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D053499:Plasma Membrane Calcium-Transporting ATPases; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D016559:Tacrolimus / Q000494:pharmacology
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D005656:Fungal Proteins; C085484:PMC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D016572:Cyclosporine; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D053499:Plasma Membrane Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; D002118:Calcium; D016559:Tacrolimus