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Mol. Cell. Biol., 03 1997, 1450-1458, Vol 17, No. 3
KM Dombek and ET Young
In Saccharomyces cerevisiae, the unregulated cyclic AMP-dependent protein
kinase (cAPK) activity of bcy1 mutant cells inhibits expression of the
glucose-repressible ADH2 gene. The transcription factor Adr1p is thought to
be the primary target of cAPK. Here we demonstrate that the decreased
abundance of Adr1p in bcy1 mutant cells contributes to the inhibition of
ADH2 expression. Activation of ADH2 transcription was blocked in bcy1
mutant cells, and UAS1, the Adr1p binding site in the ADH2 promoter, was
sufficient to mediate this effect. Concurrent with this loss of
transcriptional activation was an up to 30-fold reduction in the level of
Adr1p. Mutating the strong cAPK phosphorylation site at serine 230 did not
suppress this effect. Analysis of ADR1 mRNA levels and ADR1-lacZ expression
suggested that decreased ADR1 transcription was responsible for the reduced
protein level. In contrast to the ADH2 promoter, however, deletion analysis
suggested that cAPK does not act through a discrete DNA element in the ADR1
promoter. The amount of Adr1p found in bcy1 mutant cells should have been
sufficient to support 23% of the wild-type level of ADH2 expression. Since
no ADH2 expression was detectable in bcy1 mutant cells, cAPK must also act
by other mechanisms. Overexpression of Adr1p only partially restored ADH2
expression, indicating that some of these mechanisms may impinge upon
events at or subsequent to the ADR1-dependent step in ADH2 transcriptional
activation.
Copyright © 1997, American Society for Microbiology
Cyclic AMP-dependent protein kinase inhibits ADH2 expression in part by decreasing expression of the transcription factor gene ADR1
Department of Biochemistry, University of Washington, Seattle 98195- 7350, USA. kmd@u.washington.edu
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