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 c 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 (rEAG1190) but not the full-length rEAG1, partially complemented the growth defect of K-uptake mutant cells (trk1,2 tok1) in media containing low K concentrations. The expression of rEAG1190 in a strain lacking the cation efflux systems (nha1 ena1-4) increased the sensitivity to high monovalent cation concentrations. Both phenotypes were observed, when rEAG1190 was expressed in a trk1,2 and nha1, ena1-4 mutant strain. In the presence of K-channel blockers (Cs, Bapo and quinidine), the growth advantage of rEAG1190 expressing trk1,2 tok1 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.
展开▼
