THE UGA4 UAS(NTR) SITE REQUIRED FOR GLN3-DEPENDENT TRANSCRIPTIONAL ACTIVATION ALSO MEDIATES DAL80-RESPONSIVE REGULATION AND DAL80 PROTEIN-BINDING IN SACCHAROMYCES-CEREVISIAE

Expression of the nitrogen catabolic genes in Saccharomyces cerevisiae , including those of the gamma-aminobutyric acid (UGA) and allantoin ( DAL) pathways, is regulated positively by the GLN3 protein and negativ ely by the DAL80 protein. The deduced sequences of the DAL80 and GLN3 proteins contain a zinc finger motif homologous to those shown to bind GATA sequences. In addition, DAL80 protein has been directly shown to bind to a pair of GATA-containing sequences (URS(GATA)) in vitro, and a pair of GATA containing sequences (UAS(NTR)) is required for GLN3-d ependent transcriptional activation in a heterologous expression vecto r. We demonstrate here that the GATA-containing sites upstream of UGA4 required for optimal GLN3-dependent transcriptional activation also m ediate DAL80 protein binding in vitro and DAL80-responsive regulation in vivo