title: Role of Saccharomyces cerevisiae Trk1 in stabilization of intracellular potassium content upon changes in external potassium levels.
abstract: Saccharomyces cerevisiae cells are able to grow at very different potassium concentrations adapting its intracellular cation levels to changes in the external milieu. Potassium homeostasis in wild type cells resuspended in media with low potassium is an example of non-perfect adaptation since the same intracellular concentration is not approached irrespective of the extracellular levels of the cation. By using yeasts lacking the Trk1,2 system or expressing different versions of the mutated main plasma membrane potassium transporter (Trk1), we show that Trk1 is not essential for adaptation to potassium changes but the dynamics of potassium loss is very different in the wild type and in trk1,2 mutant or in yeasts expressing Trk1 versions with highly impaired transport characteristics. We also show that the pattern here described can be also fulfilled by heterologous expression of NcHAK1, a potassium transporter not belonging to the TRK family. Hyperpolarization and cationic drugs sensitivity in mutants with defective transport capacity provide additional support to the hypothesis of connections between the activity of the Trk system and the plasma membrane H(+) ATPase (Pma1) in the adaptive process.
authors.affiliation: Departamento de Microbiología, Universidad de Córdoba, Córdoba, Spain.
authors.forename: Rito
authors.initials: R
authors.lastname: Herrera
authors.forename: María C
authors.initials: MC
authors.lastname: Alvarez
authors.forename: Samuel
authors.initials: S
authors.lastname: Gelis
authors.forename: Marie
authors.initials: M
authors.lastname: Kodedová
authors.forename: Hana
authors.initials: H
authors.lastname: Sychrová
authors.forename: Maik
authors.initials: M
authors.lastname: Kschischo
authors.forename: José
authors.initials: J
authors.lastname: Ramos
mesh_terms: D000222:Adaptation, Physiological; D027682:Cation Transport Proteins / Q000172:deficiency / Q000235:genetics*; D002414:Cations, Monovalent; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D017136:Ion Transport; D009154:Mutation; D009492:Neurospora crassa / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*
chemical_list: D027682:Cation Transport Proteins; D002414:Cations, Monovalent; D029701:Saccharomyces cerevisiae Proteins; C068664:TRK1 protein, S cerevisiae; C092477:PMA1 protein, S cerevisiae; D006180:Proton-Translocating ATPases; D011188:Potassium
keywords: Intracellular potassium; Non-perfect adaptation; Saccharomyces cerevisiae; Trk transporter