Broad, but not universal, transcriptional requirement for yTAF_II17, a histone H3-like TAF_II 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_IIs). Experiments in yeast have shown that although most TAF_IIs are required for viability, many genes are transcribed normally upon inactivation of individual and even multiple yTAF_IIs. Here we analyze yTAF_II17, recently found to be present in both the SAGA HAT complex as well as TFIID. Functional inactivation of yTAF_II17 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_II17 dependent. In conjunction with previous studies, our results reveal that different TAF_IIs have remarkably distinct properties.