Fig. 4. TFTC preferentially acetylates mononucleosomes assembled on UV-damaged DNA templates. (A) A bead-linked 220 bp DNA fragment irradiated with increasing UV-C doses was reconstituted either with (nucleosome) or without (naked DNA) human histone octamers. Bead-linked nucleosomes (or naked DNA) were then either (B) digested with MNase, transfered to a nylon membrane and hybridized with a ³²P-labelled probe, or (C) incubated with 200 ng of TFTC or 5 ng of p300 in the presence of [³H]acetylCoA, washed and counted for incorporation of radioactivity in histones. The graph represents the average of two independent experiments performed in duplicate and is normalized for the loss of DNA due to UV irradiation. Grey column, p300; white column, TFTC.