Fig. 5. TFTC preferentially acetylates nucleosomal arrays assembled on UV-damaged DNA templates. (A) A bead-linked DNA fragment, with five copies of the 208 bp 5S rDNA nucleosome positioning sequence that allows the formation of regular nucleosomal arrays, was irradiated with increasing UV-C doses (as indicated) and reconstituted with purified human histone octamers. Bead-linked nucleosomal arrays were either digested with MNase, separated on an agarose gel and stained with ethidium bromide (asterisks indicate nucleosome boundaries), or incubated with 200 ng of TFTC in the presence (+) or absence (–) of acetyl-CoA and washed. (B) Acetylated histones were analysed by western blotting using antibodies recognizing acetylated histones. Nucleosomes assembled on the different DNA fragments were verified with antibodies recognizing non-acetylated histone H4 or acetylated histone H3. Lane 1, magnetic only beads. (C) The graph represents the acetylation of histone H3 in four independent experiments after normalization for DNA and histone content in the UV-irradiated samples. The standard deviation is given by error bars.