Distinct classes of yeast promoters revealed by differential TAF recruitment

The transcription factor TFIID contains the TATA box binding protein (TBP) and multiple TBP-associated factors (TAFs). Here, the association of TFIID components with promoters that either are dependent on multiple TAFs (TAFdep) or have no apparent TAF requirement (TAFind) is analyzed in yeast. At TAFdep promoters, TAFs are present at levels comparable to that of TBP, whereas at TAFind promoters, TAFs are present at levels that approximate background. After inactivation of several general transcription factors, including TBP, TAFs are still recruited by activators to TAFdep promoters. The results reveal two classes of promoters: at TAFind promoters, TBP is recruited in the apparent absence of TAFs, whereas at TAFdep promoters, TAFs are co-recruited with TBP in a manner consistent with direct activator-TAF interactions.