scholarly journals Cyclic AMP-dependent protein kinase inhibits ADH2 expression in part by decreasing expression of the transcription factor gene ADR1.

1997 ◽  
Vol 17 (3) ◽  
pp. 1450-1458 ◽  
Author(s):  
K M Dombek ◽  
E T 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.

1992 ◽  
Vol 12 (4) ◽  
pp. 1507-1514
Author(s):  
C L Denis ◽  
S C Fontaine ◽  
D Chase ◽  
B E Kemp ◽  
L T Bemis

Four ADR1c mutations that occur close to Ser-230 of the Saccharomyces cerevisiae transcriptional activator ADR1 and which greatly enhance the ability of ADR1 to activate ADH2 expression under glucose-repressed conditions have been shown to reduce or eliminate cyclic AMP-dependent protein kinase (cAPK) phosphorylation of Ser-230 in vitro. In addition, unregulated cAPK expression in vivo blocks ADH2 depression in an ADR1-dependent fashion in which ADR1c mutations display decreased sensitivity to unregulated cAPK activity. Taken together, these data have suggested that ADR1c mutations enhance ADR1 activity by blocking cAPK phosphorylation and inactivation of Ser-230. We have isolated and characterized an additional 17 ADR1c mutations, defining 10 different amino acid changes, that were located in the region defined by amino acids 227 through 239 of ADR1. Three observations, however, indicate that the ADR1c phenotype is not simply equivalent to a lack of cAPK phosphorylation. First, only some of these newly isolated ADR1c mutations affected the ability of yeast cAPK to phosphorylate corresponding synthetic peptides modeled on the 222 to 234 region of ADR1 in vitro. Second, we observed that strains lacking cAPK activity did not display enhanced ADH2 expression under glucose growth conditions. Third, when Ser-230 was mutated to a nonphosphorylatable residue, lack of cAPK activity led to a substantial increase in ADH2 expression under glucose-repressed conditions. Thus, while cAPK controls ADH2 expression and ADR1 is required for this control, cAPK acts by a mechanism that is independent of effects on ADR1 Ser-230. It was also observed that deletion of the ADR1c region resulted in an ADR1c phenotype. The ADR1c region is, therefore, involved in maintaining ADR1 in an inactive form. ADR1c mutations may block the binding of a repressor to ADR1 or alter the structure of ADR1 so that transcriptional activation regions become unmasked.


1991 ◽  
Vol 279 (3) ◽  
pp. 727-732 ◽  
Author(s):  
G B Sala-Newby ◽  
A K Campbell

cDNA coding for the luciferase in the firefly Photinus pyralis was amplified in vitro to generate cyclic AMP-dependent protein kinase phosphorylation sites. The DNA was transcribed and translated to generate light-emitting protein. A valine at position 217 was mutated to arginine to generate a site RRFS and the heptapeptide kemptide, the phosphorylation site of the porcine pyruvate kinase, was added at the N- or C-terminus of the luciferase. The proteins carrying phosphorylation sites were characterized for their specific activity, pI, effect of pH on the colour of the light emitted and effect of the catalytic subunit of protein kinase A in the presence of ATP. Only one of the recombinant proteins (RRFS) was significantly different from wild-type luciferase. The RRFS mutant had a lower specific activity, lower pH optimum, emitted greener light at low pH and when phosphorylated it decreased its activity by up to 80%. This latter effect was reversed by phosphatase. This recombinant protein is a good candidate to measure for the first time cyclic AMP-dependent phosphorylation in live cells.


1992 ◽  
Vol 12 (10) ◽  
pp. 4478-4485 ◽  
Author(s):  
L Li ◽  
R Heller-Harrison ◽  
M Czech ◽  
E N Olson

Differentiation of skeletal muscle cells is inhibited by the cyclic AMP (cAMP) signal transduction pathway. Here we report that the catalytic subunit of cAMP-dependent protein kinase (PKA) can substitute for cAMP and suppress muscle-specific transcription by silencing the activity of the MyoD family of regulatory factors, which includes MyoD, myogenin, myf5, and MRF4. Repression by the PKA catalytic (C) subunit is directed at the consensus sequence CANNTG, the target for DNA binding and transcriptional activation by these myogenic regulators. Phosphopeptide mapping of myogenin in vitro and in vivo revealed two PKA phosphorylation sites, both within the basic region. However, repression of myogenin function by PKA does not require direct phosphorylation of these sites but instead involves an indirect mechanism with one or more intermediate steps. Regulation of the transcriptional activity of the MyoD family by modulation of the cAMP signaling pathway may account for the inhibitory effects of certain peptide growth factors on muscle-specific gene expression and may also determine the responsiveness of different cell types to myogenic conversion by these myogenic regulators.


1992 ◽  
Vol 12 (10) ◽  
pp. 4478-4485
Author(s):  
L Li ◽  
R Heller-Harrison ◽  
M Czech ◽  
E N Olson

Differentiation of skeletal muscle cells is inhibited by the cyclic AMP (cAMP) signal transduction pathway. Here we report that the catalytic subunit of cAMP-dependent protein kinase (PKA) can substitute for cAMP and suppress muscle-specific transcription by silencing the activity of the MyoD family of regulatory factors, which includes MyoD, myogenin, myf5, and MRF4. Repression by the PKA catalytic (C) subunit is directed at the consensus sequence CANNTG, the target for DNA binding and transcriptional activation by these myogenic regulators. Phosphopeptide mapping of myogenin in vitro and in vivo revealed two PKA phosphorylation sites, both within the basic region. However, repression of myogenin function by PKA does not require direct phosphorylation of these sites but instead involves an indirect mechanism with one or more intermediate steps. Regulation of the transcriptional activity of the MyoD family by modulation of the cAMP signaling pathway may account for the inhibitory effects of certain peptide growth factors on muscle-specific gene expression and may also determine the responsiveness of different cell types to myogenic conversion by these myogenic regulators.


1992 ◽  
Vol 12 (4) ◽  
pp. 1507-1514 ◽  
Author(s):  
C L Denis ◽  
S C Fontaine ◽  
D Chase ◽  
B E Kemp ◽  
L T Bemis

Four ADR1c mutations that occur close to Ser-230 of the Saccharomyces cerevisiae transcriptional activator ADR1 and which greatly enhance the ability of ADR1 to activate ADH2 expression under glucose-repressed conditions have been shown to reduce or eliminate cyclic AMP-dependent protein kinase (cAPK) phosphorylation of Ser-230 in vitro. In addition, unregulated cAPK expression in vivo blocks ADH2 depression in an ADR1-dependent fashion in which ADR1c mutations display decreased sensitivity to unregulated cAPK activity. Taken together, these data have suggested that ADR1c mutations enhance ADR1 activity by blocking cAPK phosphorylation and inactivation of Ser-230. We have isolated and characterized an additional 17 ADR1c mutations, defining 10 different amino acid changes, that were located in the region defined by amino acids 227 through 239 of ADR1. Three observations, however, indicate that the ADR1c phenotype is not simply equivalent to a lack of cAPK phosphorylation. First, only some of these newly isolated ADR1c mutations affected the ability of yeast cAPK to phosphorylate corresponding synthetic peptides modeled on the 222 to 234 region of ADR1 in vitro. Second, we observed that strains lacking cAPK activity did not display enhanced ADH2 expression under glucose growth conditions. Third, when Ser-230 was mutated to a nonphosphorylatable residue, lack of cAPK activity led to a substantial increase in ADH2 expression under glucose-repressed conditions. Thus, while cAPK controls ADH2 expression and ADR1 is required for this control, cAPK acts by a mechanism that is independent of effects on ADR1 Ser-230. It was also observed that deletion of the ADR1c region resulted in an ADR1c phenotype. The ADR1c region is, therefore, involved in maintaining ADR1 in an inactive form. ADR1c mutations may block the binding of a repressor to ADR1 or alter the structure of ADR1 so that transcriptional activation regions become unmasked.


2000 ◽  
Vol 74 (3) ◽  
pp. 949-959 ◽  
Author(s):  
Yu Nakamura ◽  
Ryota Hashimoto ◽  
Yujiro Kashiwagi ◽  
Saburo Aimoto ◽  
Eriko Fukusho ◽  
...  

1992 ◽  
Vol 287 (3) ◽  
pp. 791-795 ◽  
Author(s):  
E A Carrey

The multienzyme polypeptide CAD is phosphorylated at two sites by cyclic AMP (cAMP)-dependent protein kinase. Site 2 has two interesting features: it is located in a ‘linking region’ between two discretely folded enzyme domains, and a histidine, instead of the more usual arginine, is found three positions N-terminal to the phosphorylated serine. A synthetic peptide corresponding to the sequence around site 2 has an extended or random structure in solution, and the proton n.m.r. chemical shift of the histidine residues can be titrated against pH in the range 6.0-8.0. The peptide is phosphorylated more rapidly by cAMP-dependent protein kinase at lower pH values, indicating that the protonated histidine side chain corresponds to the arginine in the consensus recognition sequence for the kinase. Kemptide, a specific synthetic substrate for the kinase, was phosphorylated with a higher affinity and at a similar rate at all pH values. CAD was a better substrate than the synthetic peptide, and labelling was not affected by the pH of the incubation conditions. The results indicate that the phosphorylation site in the interdomain linker is sufficiently exposed to the solvent to ensure accessibility to the kinase, but that secondary or tertiary structure in the intact protein allows the histidine residue to remain protonated at physiological pH and enhances recognition of the phosphorylatable serine residue.


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