CHARACTERIZATION OF A P53-RELATED ACTIVATION DOMAIN IN ADR1P THAT IS SUFFICIENT FOR ADR1-DEPENDENT GENE-EXPRESSION

The yeast transcriptional activator Adr1p controls expression of the g lucose-repressible alcohol dehydrogenase gene (ADH2), genes involved i n glycerol metabolism, and genes required for peroxisome biogenesis an d function. Previous data suggested that promoter-specific activation domains might contribute to expression of the different types of ADR1- dependent genes, By using gene fusions encoding: the Gal4p DNA binding domain and portions of Adr1p, we identified a single, strong acidic a ctivation domain spanning amino acids 420-462 of Adr1p. Both acidic an d hydrophobic amino acids within this activation domain were important for its function. The critical hydrophobic residues are in a motif pr eviously identified in p53 and related acidic activators. A mini-Adr1 protein consisting of the DNA binding domain of Adr1p fused to this 42 -residue activation domain carried out all of the known functions of w ild-type ADR1. It conferred stringent glucose repression on the ADH2 l ocus and on UAS1-containing reporter genes. The putative inhibitory re gion of Adr1p encompassing the protein kinase A phosphorylation site a t Ser-230 is thus not essential for glucose repression mediated by ADR 1. Mini-ADR1 allowed efficient derepression of gene expression. In add ition it complemented an ADR1-null allele for growth on glycerol and o leate media, indicating efficient activation of genes required for gly cerol metabolism and peroxisome biogenesis. Thus, a single activation domain can activate all ADR1-dependent promoters.