Figure 5

The histone acetyltransferase activity of Gcn5 is required for transcriptional elongation. The figure shows serial dilutions of wild type (wt) and mutant (gcn5Δ, tfIIsΔ, and gcn5Δ expressing different gcn5 HAT domain mutants) yeast cells spotted on normal growth media (control) or media containing the transcription elongation inhibitor, mycophenolic acid (MPA), or MPA together with extra Guanine (G), which counteracts the inhibition activity of MPA. Gcn5 derivatives expressed from plasmids are shown in square brakets: [GCN5] – wild type GCN5 and [GCN5-PKE] - HAT domain mutant with full catalytic activity as well as [GCN5-KQL] and [GCN5-PKM] HAT domain mutants with strongly reduced histone acetyltransferase activity (see [9]). TFIIS is an important basal transcription factor involved in transcriptional elongation.