Trinucleotide insertions, deletions, and point mutations in glucose transporters confer K+ uptake in Saccharomyces cerevisiae.

ABSTRACT: Deletion of TRK1 and TRK2 abolishes high-affinity K+ uptake in Saccharomyces cerevisiae, resulting in the inability to grow on typical synthetic growth medium unless it is supplemented with very high concentrations of potassium. Selection for spontaneous suppressors that restored growth of trk1delta trk2delta cells on K+-limiting medium led to the isolation of cells with unusual gain-of-function mutations in the glucose transporter genes HXT1 and HXT3 and the glucose/galactose transporter gene GAL2. 86Rb uptake assays demonstrated that the suppressor mutations conferred increased uptake of the ion. In addition to K+, the mutant hexose transporters also conferred permeation of other cations, including Na+. Because the selection strategy required such gain of function, mutations that disrupt

SUBMITTER: Liang H 

PROVIDER: S-EPMC108804 | biostudies-literature | 1998 Feb

REPOSITORIES: biostudies-literature