Protein phosphatase type 1 regulates ion homeostasis in Saccharomyces cerevisiae.
Protein phosphatase type 1 (PP1) is encoded by the essential gene GLC7 in Saccharomyces cerevisiae. glc7-109 (K259A, R260A) has a dominant, hyperglycogen defect and a recessive, ion and drug sensitivity. Surprisingly, the hyperglycogen phenotype is partially retained in null mutants of GAC1, GIP2, and PIG1, which encode potential glycogen-targeting subunits of Glc7. The R260A substitution in GLC7 is responsible for the dominant and recessive traits of glc7-109. Another mutation at this residue, glc7-R260P, confers only salt sensitivity, indicating that the glycogen and salt traits of glc7-109 are due to defects in distinct physiological pathways. The glc7-109 mutant is sensitive to cations, aminoglycosides, and alkaline pH and exhibits increased rates of l-leucine and 3,3'-dihexyloxacarbocyanine iodide uptake, but it is resistant to molar concentrations of sorbitol or KCl, indicating that it has normal osmoregulation. KCl suppresses the ion and drug sensitivities of the glc7-109 mutant. The CsCl sensitivity of this mutant is suppressed by recessive mutations in PMA1, which encodes the essential plasma membrane H(+)ATPase. Together, these results indicate that Glc7 regulates ion homeostasis by controlling ion transport and/or plasma membrane potential, a new role for Glc7 in budding yeast.
Williams-Hart
Tara
T
Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130, USA.
Wu
Xiaolin
X
Tatchell
Kelly
K
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000378:metabolism; D019703:Calcineurin / Q000378:metabolism; D002586:Cesium / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000378:metabolism; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D002586:Cesium; D012965:Sodium Chloride; D006003:Glycogen; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; C092477:PMA1 protein, S cerevisiae; D006180:Proton-Translocating ATPases; D007930:Leucine; D011188:Potassium