Functional expression of the voltage-gated neuronal mammalian potassium channel rat ether à go-go1 in yeast

• Published in: FEMS yeast research 2008-05, Vol.8 (3), p.405-413
• Main Authors: Schwarzer, Sarah, Kolacna, Lucie, Lichtenberg-Fraté, Hella, Sychrova, Hana, Ludwig, Jost
• Format: Article
• Language: English
• Subjects: Animals; Barium Compounds - pharmacology; Chlorides - pharmacology; Ether-A-Go-Go Potassium Channels - genetics; Ether-A-Go-Go Potassium Channels - physiology; Hydrogen-Ion Concentration; Mammals; Metal ions; Mutants; N-Terminus; Phenotypes; Potassium; Potassium - metabolism; Potassium Channel Blockers - pharmacology; Potassium channels; Potassium channels (inwardly-rectifying); Potassium channels (voltage-gated); Quinidine; Rats; Recombinant Proteins - metabolism; Rubidium - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Yeast
• ISSN: 1567-1356; 1567-1364
• DOI: 10.1111/j.1567-1364.2007.00351.x

It has been shown previously that heterologous expression of inwardly rectifying potassium channels (K⁺-channels) from plants and mammals in K⁺-transport defective yeast mutants can restore the ability of growth in media with low [K⁺]. In this study, the functional expression of an outward rectifying mammalian K⁺-channel in yeast is presented for the first time. The outward-rectifying mammalian neuronal K⁺-channel rat ether à go-go channel 1 (rEAG1, Kv 10.1) was expressed in yeast (Saccharomyces cerevisiae) strains lacking the endogenous K⁺-uptake systems and/or alkali-metal-cation efflux systems. It was found that a truncated channel version, lacking almost the complete intracellular N-terminus (rEAG1Δ190) but not the full-length rEAG1, partially complemented the growth defect of K⁺-uptake mutant cells (trk1,2Δ tok1Δ) in media containing low K⁺ concentrations. The expression of rEAG1Δ190 in a strain lacking the cation efflux systems (nha1Δ ena1-4Δ) increased the sensitivity to high monovalent cation concentrations. Both phenotypes were observed, when rEAG1Δ190 was expressed in a trk1,2Δ and nha1, ena1-4Δ mutant strain. In the presence of K⁺-channel blockers (Cs⁺, Ba²⁺ and quinidine), the growth advantage of rEAG1Δ190 expressing trk1,2 tok1Δ cells disappeared, indicating its dependence on functional rEAG1 channels. The results demonstrate that S. cerevisiae is a suitable expression system even for voltage-gated outward-rectifying mammalian K⁺-channels.