Figure 1.

Disruption of HGT1, encoding a high-affinity glutathione uptake transporter, and a broad range of other genes leads to overaccumulation of extracellular glutathione in stationary phase cultures of S. cerevisiae. (A; inset) The parental strain (BY4743) and hgt1 mutant were grown to stationary phase (2 d) in SD medium, and final cell yield (open bars; A₆₀₀) and extracellular glutathione (closed bars; μmol/A₆₀₀) were quantified. (B) Frequency distribution of extracellular glutathione accumulated by each of the deletion mutants analyzed in this study. Deletion mutants pregrown in YPD medium (3 d) were diluted (1/10) and inoculated in SD medium by using a 96 pin replicator (initial A₆₀₀ of <0.01). Cells were incubated at 30°C for 3 d (without agitation), and extracellular glutathione was quantified. High-range glutathione overexcretion occurred predominantly after deletion of genes encoding functions associated with the late endosome and vacuole (under these conditions the parental strain excreted 1-2 μM glutathione).