Saccharomyces cerevisiae basic region-leucine zipper protein regulatory networks converge at the ATR1 structural gene

Saccharomyces cerevisiae cells express a family of transcription factors belonging to the basic region-leucine zipper family. Two of these proteins, yAP-1 and Gcn4p, are known to be involved in oxidative stress tolerance and general control of amino acid biosynthesis, respectively. Strains lacking the YAP1 or GCN4 structural gene have very different phenotypes, which have been taken as evidence that these transcriptional regulatory proteins control separate batteries of target genes. In this study, we provide evidence that both yAP-1 and Gcn4p control the expression of a putative integral membrane protein, Atr1p. Both yAP-1 and Gcn4p can elevate resistance to 3-amino-1,2,4-triazole and 4-nitroquinoline-N-oxide but only if the ATR1 gene is intact. Expression of ATR1 is enhanced in the presence of constitutively active alleles of YAP1 and GCN4. Regulation of ATR1 transcription by yAP-1 and Gcn4p occurs through a common DNA element related to the yAP-1 recognition element found upstream of other yAP-1-regulated genes. These data provide the first indication of overlap between the regulatory networks defined by yAP-1 and Gcn4p.