Transcriptional activation in yeast cells lacking transcription factor IIA

The general transcription factor IIA (TFIIA) forms a complex with TFIID at the TATA promoter element, and it inhibits the function of several negative regulators of the TATA-binding protein (TBP) subunit of TFIID. Biochemical experiments suggest that TFIIA is important in the response to transcripti onal activators because activation domains can interact dth TFIIA, increase recruitment of TFIID and TFIIA to the promoter, and promote isomerization of the TFIID-TFIIA-TATA complex. Here, we describe a double-shut-off approa ch to deplete yeast cells of Teal, the large subunit of TFIIA, to <1% of th e wildtype level. Interestingly, such TFIIA-depleted cells are essentially unaffected for activation by heat shock factor, Ace1, and Gal4-VP16. Howeve r, depletion of TFIIA causes a general two- to threefold decrease of transc ription from most yeast promoters and a specific cell-cycle arrest at the G 2-M boundary. These results indicate that transcriptional activation in viv o can occur in the absence of TFIIA.