Journal of Fungi (May 2021)

The Potassium Transporter Hak1 in <i>Candida Albicans,</i> Regulation and Physiological Effects at Limiting Potassium and under Acidic Conditions

  • Francisco J. Ruiz-Castilla,
  • Elisa Rodríguez-Castro,
  • Carmen Michán,
  • José Ramos

DOI
https://doi.org/10.3390/jof7050362
Journal volume & issue
Vol. 7, no. 5
p. 362

Abstract

Read online

The three families of yeast plasma membrane potassium influx transporters are represented in Candida albicans: Trk, Acu, and Hak proteins. Hak transporters work as K+-H+ symporters, and the genes coding for Hak proteins are transcriptionally activated under potassium limitation. This work shows that C. albicans mutant cells lacking CaHAK1 display a severe growth impairment at limiting potassium concentrations under acidic conditions. This is the consequence of a defective capacity to transport K+, as indicated by potassium absorption experiments and by the kinetics parameters of Rb+ (K+) transport. Moreover, hak1− cells are more sensitive to the toxic cation lithium. All these phenotypes became much less robust or even disappeared at alkaline growth conditions. Finally, transcriptional studies demonstrate that the hak1− mutant, in comparison with HAK1+ cells, activates the expression of the K+/Na+ ATPase coded by CaACU1 in the presence of Na+ or in the absence of K+.

Keywords