Individual functions of the HAK and TRK potassium transporters of Schwanniomyces occidentalis.
We have cloned the gene encoding the TRK transporter of the soil yeast Schwanniomyces occidentalis and obtained the HAK1 trk1 delta and the hak1 delta TRK1 mutant strains. Analyses of the transport capacities of these mutants have shown that (i) the HAK1 and the TRK1 potassium transporters are the only transporters operating at low and medium K+ concentrations (< 1 mM); (ii) the HAK1 transporter is functional at low pH but fails at high pH; and (iii) the TRK1 transporter functions at neutral and high pH and fails at low pH. At neutral pH, both transporters are functional, but HAK1 is not expressed, except at very low K+ concentrations (< 50 microM) where HAK1 is very effective. TRK1 is also involved in the control of the membrane potential.
Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
M A
MA
Bañuelos
R
R
Madrid
A
A
Rodríguez-Navarro
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017136:Ion Transport; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011188:Potassium / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D004718:Saccharomycetales / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; D027682:Cation Transport Proteins; D005656:Fungal Proteins; C491725:HAK1 protein, Schwanniomyces occidentalis; D008565:Membrane Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C068664:TRK1 protein, S cerevisiae; D011188:Potassium