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Molecular and Cellular Biology, December 1999, p. 8302-8313, Vol. 19, No. 12
Department of Physiology and Biophysics,
University of Iowa, Iowa City, Iowa 52242
Received 14 April 1999/Returned for modification 25 May
1999/Accepted 25 August 1999
Positive regulation of gene expression by the yeast
Saccharomyces cerevisiae transcription factor Yap1p is
required for normal tolerance of oxidative stress elicited by the
redox-active agents diamide and H2O2. Several
groups have provided evidence that a cluster of cysteine residues in
the extreme C terminus of the factor are required for normal modulation
of Yap1p by oxidant challenge. Deletion of this C-terminal
cysteine-rich domain (c-CRD) produces a protein that is highly active
under both stressed and nonstressed conditions and is constitutively
located in the nucleus. We have found that a variety of different c-CRD
mutant proteins are hyperactive in terms of their ability to confer
diamide tolerance to cells but fail to provide even normal levels of
H2O2 resistance. Although the c-CRD mutant
forms of Yap1p activate an artificial Yap1p-responsive gene to the same
high level in the presence of either diamide or
H2O2, these mutant factors confer
hyperresistance to diamide but hypersensitivity to
H2O2. To address this discrepancy, we have
examined the ability of c-CRD mutant forms of Yap1p to activate
expression of an authentic target gene required for
H2O2 tolerance, TRX2. When assayed
in the presence of c-CRD mutant forms of Yap1p, a TRX2-lacZ
fusion gene fails to induce in response to
H2O2. We have also identified a second
cysteine-rich domain, in the N terminus (n-CRD), that is required for
H2O2 but not diamide resistance and influences
the localization of the protein. These data are consistent with the
idea that the function of Yap1p is different at promoters of loci
involved in H2O2 tolerance from promoters of
genes involved in diamide resistance.
0270-7306/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Yap1p Activates Gene Transcription in an Oxidant-Specific
Fashion
and
*
Corresponding author. Mailing address: Department of
Physiology and Biophysics, University of Iowa, Iowa City, IA 52242. Phone: (319)-335-7874. Fax: (319)-335-7330. E-mail:
moyerowl{at}blue.weeg.uiowa.edu.
Present address: Department of Biochemistry, Health Sciences
Center, University of Virginia, Charlottesville, VA 22908.
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