title: Ion tolerance of Saccharomyces cerevisiae lacking the Ca2+/CaM-dependent phosphatase (calcineurin) is improved by mutations in URE2 or PMA1.
abstract: Calcineurin is a conserved, Ca2+/CaM-stimulated protein phosphatase required for Ca2+-dependent signaling in many cell types. In yeast, calcineurin is essential for growth in high concentrations of Na+, Li+, Mn2+, and OH-, and for maintaining viability during prolonged treatment with mating pheromone. In contrast, the growth of calcineurin-mutant yeast is better than that of wild-type cells in the presence of high concentrations of Ca2+. We identified mutations that suppress multiple growth defects of calcineurin-deficient yeast (cnb1Delta or cna1Delta cna2Delta). Mutations in URE2 suppress the sensitivity of calcineurin mutants to Na+, Li+, and Mn2+, and increase their survival during treatment with mating pheromone. ure2 mutations require both the transcription factor Gln3p and the Na+ ATPase Pmr2p to confer Na+ and Li+ tolerance. Mutations in PMA1, which encodes the yeast plasma membrane H+-ATPase, also suppress many growth defects of calcineurin mutants. pma1 mutants display growth phenotypes that are opposite to those of calcineurin mutants; they are resistant to Na+, Li+, and Mn2+, and sensitive to Ca2+. We also show that calcineurin mutants are sensitive to aminoglycoside antibiotics such as hygromycin B while pma1 mutants are more resistant than wild type. Furthermore, pma1 and calcineurin mutations have antagonistic effects on intracellular [Na+] and [Ca2+]. Finally, we show that yeast expressing a constitutively active allele of calcineurin display pma1-like phenotypes, and that membranes from these yeast have decreased levels of Pma1p activity. These studies further characterize the roles that URE2 and PMA1 play in regulating intracellular ion homeostasis.
authors.affiliation: Department of Biological Sciences, Stanford University, Stanford, California 94305-5020, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Withee
authors.forename: R
authors.initials: R
authors.lastname: Sen
authors.forename: M S
authors.initials: MS
authors.lastname: Cyert
mesh_terms: D000251:Adenosine Triphosphatases / Q000502:physiology; D019703:Calcineurin / Q000172:deficiency* / Q000235:genetics* / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors / Q000494:pharmacology; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins / Q000502:physiology; D004352:Drug Resistance, Microbial; D004789:Enzyme Activation / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics* / Q000502:physiology; D005800:Genes, Fungal / Q000187:drug effects; D005979:Glutathione Peroxidase; D006706:Homeostasis / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D006921:Hygromycin B / Q000494:pharmacology; D017136:Ion Transport / Q000187:drug effects / Q000235:genetics; D008094:Lithium / Q000378:metabolism / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D009154:Mutation; D011328:Prions; D006180:Proton-Translocating ATPases / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D012964:Sodium / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase; D014157:Transcription Factors
chemical_list: D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; C086375:ENA1 protein, S cerevisiae; D005656:Fungal Proteins; C071664:GLN3 protein, S cerevisiae; C434364:PMA2 protein, S cerevisiae; D011328:Prions; D012097:Repressor Proteins; C091044:SCN1 protein, S pombe; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; D006921:Hygromycin B; D008345:Manganese; D008094:Lithium; D012964:Sodium; D005979:Glutathione Peroxidase; C067020:URE2 protein, S cerevisiae; D019703:Calcineurin; D000251:Adenosine Triphosphatases; C092477:PMA1 protein, S cerevisiae; D006180:Proton-Translocating ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium