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 (TAFIIs). Experiments in yeast have shown that although most TAFIIs are required for viability, many genes are transcribed normally upon inactivation of individual and even multiple yTAFIIs. Here we analyze yTAFII17, recently found to be present in both the SAGA HAT complex as well as TFIID. Functional inactivation of yTAFII17 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 yTAFII17 dependent. In conjunction with previous studies, our results reveal that different TAFIIs have remarkably distinct properties.