Analysis of URS(G)-mediated glucose repression of the GAL1 promoter of Saccharomyces cerevisiae

Abstract

Repression of GAL1 expression during growth on glucose is mediated in part by cis-acting promoter elements designated URS(G). We show that oligonucleotides containing sequences from two regions of URS(G) confer glucose repression upon a heterologous promoter. Repression caused by URS(G) is dependent on trans-acting factors of the glucose repression pathway and is independent of orientation or location within a promoter, suggesting that URS(G) contains binding sites for a glucose-activated repressor protein(s). Genetic analysis identified three apparently novel genes (URR1, URR3 and URR4) that are specifically required for URS(G)-mediated repression and may encode such repressor proteins. Mutations in the URR genes suppress the defect in URS(G) derepression caused by a snf1 mutation.