Genomic screen reveals genes required for normal Yap1p trafficking
during oxidant challenge in Saccharomyces cerevisiae .
Sherry A. Rovinsky, W. Scott Moye-Rowley
Physiology and Biophysics, The University of Iowa, 6-513 Bowen, Iowa
City, IA 52242, USA
The transcription factor Yap1p accumulates in the nucleus during oxidant
challenge and activates transcription of genes responsible for normal
oxidant tolerance in Saccharomyces cerevisiae. This regulated
nuclear accumulation of Yap1p is thought to occur via a decrease in the
rate of nuclear export of the protein. To identify genes involved in
regulation of Yap1p-mediated H2O2 resistance, we
have conducted a large-scale screen using a haploid gene deletion
library. We found a large number of H2O2 sensitive
mutants and screened a group of these for defects in the expression of
TRX2, a key Yap1p-regulated gene required for normal
H2O2 tolerance, and stress-responsive nuclear
localization of Yap1p. Five mutants were found that exhibited an
alteration in trafficking of Yap1p during H2O2
stress. Each mutant showed the usual cytoplasmic localization of Yap1p
under non-stressed conditions. However, upon H2O2
exposure, these five mutant strains exhibited perinuclear localization,
quite different from the normal intranuclear location of this
transcription factor. Trafficking of another, unrelated transcription
factor is normal in these strains. These five mutants include a defect
in a gene of unknown function that was identified by others as a 2
hybrid positive with Yap1p. The observation that perinuclear
localization of Yap1p is seen only under H2O2
challenge in these mutant strains suggests the presence of an additional
regulated step during Yap1p nuclear localization.
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