Broad, but not universal, transcriptional requirement for yTAFII17, a histone H3-like TAFII present in TFIID and SAGA

The RNA polymerase II general transcription factor TFIID is a multisubunit complex comprising TATA box-binding protein (TBP) and associated factors (TAF(II)s). Experiments in yeast have shown that although most TAF(II)s are required for viability, many genes are transcribed normally upon inactivation of individual and even multiple yTAF(II)s. Here we analyze yTAF(II)17, recently found to be present in both the SAGA HAT complex as well as TFIID. Functional inactivation of yTAF(II)17 by temperature-sensitive mutation or depletion results in loss of transcription of many, but not all, genes. The upstream activating sequence (UAS), which contains the activator binding sites, is the region that renders a gene yTAF(II)17 dependent. In conjunction with previous studies, our results reveal that different TAF(II)s have remarkably distinct properties.