MAP kinase and cAMP filamentation signaling pathways converge on the unusually large promoter of the yeast FLO11 gene

In Saccharomyces cerevisiae, two major signal transduction pathways, the Ks s1 MAPK pathway and the cAMP-regulated pathway, are critical for the differ entiation of round yeast form cells to multicellular, invasive pseudohyphae . Here we report that these parallel pathways converge on the promoter of a gene, FLO11, which encodes a cell surface protein required for pseudohypha l formation. The FLO11 promoter is unusually large, containing at least fou r upstream activation sequences (UASs) and nine repression elements which t ogether span at least 2.8 kb, Several lines of evidence indicate that the M APK and cAMP signals are received by distinct transcription factors and pro moter elements. First, regulation via the MAPK pathway requires the transcr iption factors Ste12p/Tec1p, whereas cAMP-mediated activation requires a di stinct factor, Flo8p, Secondly, mutations in either pathway block FLO11 tra nscription. Overexpression of STE12 can suppress the loss of FLO8, and over expression of FLO8 can suppress the loss of STE12, Finally, multiple distin ct promoter regions of the FLO11 promoter are required for its activation b y either Flo8p or Ste12p/Tec1p, Thus, like the promoters of the key develop mental genes, HO and IME1, the FLO11 promoter is large and complex, endowin g it with the ability to integrate multiple inputs.