Kg. Sharma et al., Glutathione depletion leads to delayed growth stasis in Saccharomyces cerevisiae: evidence of a partially overlapping role for thioredoxin, CURR GENET, 38(2), 2000, pp. 71-77
Disruption of the first enzyme of glutathione biosynthesis in both Saccharo
myces cerevisiae and Schizosaccharomyces pombe leads to a glutathione auxot
rophy phenotype on plates. However, growth experiments in liquid medium rev
ealed that the cessation of growth resulting from glutathione depletion in
these yeasts is very delayed in S. cerevisiae compared to S. pombe. Glutath
ione metabolism was investigated to understand this delayed growth stasis i
n S. cerevisiae. The assimilation of reduced and oxidized glutathione, the
intracellular storage pools of glutathione and the turnover of this compoun
d were investigated and found to be similar in both yeasts. A possible over
lapping role of intracellular thioredoxin in causing delayed stasis was stu
died. Yeast thioredoxin was overexpressed in S. cerevisiae and was found to
partially relieve the dependence of S. cerevisiae glutathione auxotrophs o
n extracellular glutathione in glucose-grown cultures, as well as in glycer
ol-grown cultures where conditions of increased glutathione requirements ex
ists in the cell. By partially, but not completely, compensating for glutat
hione deficiency in this yeast, thioredoxin thus appeared to be the major f
actor that was causing the delayed growth stasis following glutathione depl
etion in this yeast.