Analysis of positive elements sensitive to glucose in the promoter of the FBP1 gene from yeast

Abstract

We have identified in the promoter of the FBP1 gene from Saccharomyces cerevisiae, which codes for fructose-1,6-bisphosphatase, two elements which can form specific DNA.protein complexes and which confer glucose-repressed expression to an heterologous reporter gene. Complex formation and activation of transcription by either element require a functional CAT1 gene and are not blocked by a hap2-1 mutation, although this mutation interferes with maximal expression of the FBP1 gene. A sequence from one of the elements acts as a weak upstream activating sequence, but its activity can be stimulated up to 10-fold by neighboring sequences. A further element of the promoter has been characterized, which forms a specific DNA.protein complex only when a nuclear extract from derepressed cells is used. This element does not activate transcription in a heterologous promoter. The DNA sequences of the three elements involved in protein binding, defined by DNase I footprinting, have no homology with consensus sequences for known activating factors.