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 γ-aminobutyric acid (UGA) and allantoin (DAL) pathways, is regulated positively by the GLN3 protein and negatively 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-dependent transcriptional activation in a heterologous expression vector. We demonstrate here that the GATA-containing sites upstream of UGA4 required for optimal GLN3-dependent transcriptional activation also mediate DAL80 protein binding in vitro and DAL80-responsive regulation in vivo.