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- Title
Characterization of potassium transport in wild-type and isogenic yeast strains carrying all combinations of trk1, trk2 and tok1 null mutations.
- Authors
Bertl, Adam; Ramos, José; Ludwig, Jost; Lichtenberg-Fraté, Hella; Reid, John; Bihler, Hermann; Calero, Fernando; Martínez, Paula; Ljungdahl, Per O
- Abstract
Saccharomyces cerevisiae cells express three defined potassium-specific transport systems en-coded by TRK1, TRK2 and TOK1. To gain a more complete understanding of the physiological function of these transport proteins, we have constructed a set of isogenic yeast strains carrying all combinations of trk1delta, trk2delta and tok1delta null mutations. The in vivo K+ transport characteristics of each strain have been documented using growth-based assays, and the in vitro biochemical and electrophysiological properties associated with K+ transport have been determined. As has been reported previously, Trk1p and Trk2p facilitate high-affinity potassium uptake and appear to be functionally redundant under a wide range of environmental conditions. In the absence of TRK1 and TRK2, strains lack the ability specifically to take up K+, and trk1deltatrk2delta double mutant cells depend upon poorly understood non-specific cation uptake mechanisms for growth. Under conditions that impair the activity of the non-specific uptake system, termed NSC1, we have found that the presence of functional Tok1p renders cells sensitive to Cs+. Based on this finding, we have established a growth-based assay that monitors the in vivo activity of Tok1p.
- Publication
Molecular microbiology, 2003, Vol 47, Issue 3, p767
- ISSN
0950-382X
- Publication type
Journal Article
- DOI
10.1046/j.1365-2958.2003.03335.x