THE SACCHAROMYCES-CEREVISIAE DAL80 REPRESSOR PROTEIN BINDS TO MULTIPLE COPIES OF GATAA-CONTAINING SEQUENCES (URS(GATA))

Induced expression of the allantoin (DAL) catabolic genes in Saccharom yces cerevisiae has been suggested to be mediated by interaction of th ree different types of promoter elements. First is an inducer-independ ent upstream activation sequence, UAS(NTR), whose operation is sensiti ve to nitrogen catabolite repression. The GLN3 product is required for UAS(NTR)-mediated transcriptional activation. This site consists of t wo separated elements, each of which has a GATAA sequence at its core. Response of the DAL genes to inducer is mediated by a second type of cis-acting element, DAL UIS. The DAL82 and DAL81 genes are required fo r response to inducer; DAL82 protein is the UIS-binding protein. When only the UAS(NTR) and UIS elements are present, DAL gene expression oc curs at high levels in the absence of inducer. We, therefore, hypothes ized that a third element, an upstream repressor sequence (URS) mediat es maintenance of DAL gene expression at a low level when inducer is a bsent. Since the DAL and UGA genes are overexpressed and largely induc er independent in dal80 deletion mutants, we have suggested DAL80 prot ein negatively regulates a wide spectrum of nitrogen-catabolic gene ex pression, likely in conjunction with a URS element. Here we show that DAL80 protein binds to DAL3 and UGA4 upstream DNA sequences, designate d URS(GATA), consisting of two GATAA-containing sites separated by at least 15 bp. The preferred orientation of the sites is tail to tail, b ut reasonable binding activity is also observed with a head-to-tail co nfiguration. URS(GATA) elements contain the sequence GATAA at their co re and hence share sequence homology with UAS(NTR) elements.