Differential regulation of a Tec1-Ste12 transcription factor complex during invasive growth and mating in Saccharomyces cerevisiae.
Song Chou, Haoping Liu
Biological Chemistry, Univ. of California, Irvine, 19182 Jamboree Rd., Irvine, CA, 92697, U.S.A.
Certain transcription factors can receive signals from different cell signaling pathways to control distinct developmental programs. In Saccharomyces cerevisiae, Ste12 is regulated by both mating and filamentation MAP kinase cascades, and is essential for both transcriptional programs. Cooperative interaction of Ste12 and Tec1 on FRE (a tandem Ste12 and Tec binding site) is thought to define the specificity for the filamentation transcriptional program. We find that Ste12 forms a tight complex with Tec1 and Dig1 in vivo. This complex is distinct from that of Ste12 with Dig1 and Dig2, which regulates mating. Tec1 transcriptional activity is determined by its association with Ste12, and Dig1 interaction and repression of Tec1 is also through Ste12. Furthermore, most of the filamentation genes do not have FRE elements in their promoters, but they all have Tec1 binding sites. The Tec1-Ste12-Dig1 complex, but not Ste12-Dig1-Dig2 complex, is located upstream of filamentation genes. We suggest that the filamentation transcriptional program is regulated by the Tec1-Ste12-Dig1 complex via Tec1 binding sites. The differential regulation of the two Ste12 complexes during filamentation and mating will be presented.
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