Regulation of Trk-dependent potassium transport by the calcineurin pathway involves the Hal5 kinase.
The phosphatase calcineurin and the kinases Hal4/Hal5 regulate high-affinity potassium uptake in Saccharomyces cerevisiae through the Trk1 transporter. We demonstrate that calcineurin is necessary for high-affinity potassium uptake even in the absence of Na(+) stress. HAL5 expression is induced in response to stress in a calcineurin-dependent manner through a newly identified functional CDRE (nt -195/-189). Lack of calcineurin decreases Hal5 protein levels, although with little effect on Trk1 amounts. However, the growth defect of cnb1 cells at K(+)-limiting conditions can be rescued in part by overexpression of HAL5, and this mutation further aggravates the potassium requirements of a hal4 strain. This suggests that the control exerted by calcineurin on Hal5 expression may be biologically relevant for Trk1 regulation.
Casado
Carlos
C
Departament de Bioquímica i Biologia Molecular, Universitat Autónoma de Barcelona, Barcelona, Spain.
Yenush
Lynne
L
Melero
Carmen
C
Ruiz
María del Carmen
Mdel C
Serrano
Raquel
R
Pérez-Valle
Jorge
J
Ariño
Joaquín
J
Ramos
José
J
D001692:Biological Transport / Q000235:genetics; D019703:Calcineurin / Q000378:metabolism*; D017136:Ion Transport / Q000235:genetics; D007477:Ions / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism*; D009154:Mutation; D011188:Potassium / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
D007477:Ions; D026901:Membrane Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C522341:Hal5 protein, S cerevisiae; D019703:Calcineurin; D011188:Potassium