Combinatorial control by the protein kinases PKA, PHO85 and SNF1 of transcriptional induction of the Saccharomyces cerevisiae GSY2 gene at the diauxic shift
Abstract
Genes involved in storage carbohydrate metabolism are coordinately induced when yeast cells are subjected to conditions of stress, or when they exit the exponential growth phase on glucose. We show that the STress Responsive Elements (STREs) present in the promoter of GSY2 are essential for gene activation under conditions of stress, but dispensable for gene induction and glycogen accumulation at the diauxic shift on glucose. Using serial promoter deletion, we found that the latter induction could not be attributed to a single cis -regulatory sequence, and present evidence that this mechanism depends on combinatorial transcriptional control by signalling pathways involving the protein kinases Pho85, Snf1 and PKA. Two contiguous regions upstream of the GSY2 coding region are necessary for negative control by the cyclin-dependent protein kinase Pho85, one of which is a 14-bp G/C-rich sequence. Positive control by Snf1 is mediated by Mig1p, which acts indirectly on the distal part of the GSY2 promoter. The PKA pathway has the most pronounced effect on GSY2, since transcription of this gene is almost completely abolished in an ira1ira2 mutant strain in which PKA is hyperactive. The potent negative effect of PKA is dependent upon a ...Continue Reading
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Temporal system-level organization of the switch from glycolytic to gluconeogenic operation in yeast
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