Figure 2.

The acetylation of nucleosomal core histones by p300 requires Gal4-binding sites in the template and the VP16 activation domain. Plasmid DNA templates were assembled into chromatin by ACF and NAP-1. After a 4 hr incubation to allow for the completion of chromatin assembly, Gal4–VP16 or Gal4(1-147) (i.e., the Gal4 DNA-binding domain alone), as well as increasing amounts of purified recombinant p300, were added as indicated in the presence ³H-acetyl CoA. The samples were analyzed on 12% polyacrylamide gels and the acetylated core histones were detected by fluorography. (A) Experiments using a plasmid (pIE0) lacking Gal4 binding sites. (B) Experiments using a plasmid (pGIE0) containing five Gal4 binding sites.