ABSTRACT
Extensive regions of chromatin characterized by large numbers of acetylated lysine residues on histone H3 are almost always associated with actively transcribed regions of the genome. Such acetylated regions tend to adopt chromatin conformations that are more readily accessible to the transcription machinery than areas in which acetylated histones are fewer or absent. This chapter provides a discussion on what is known about histone acetylation. The normal targets of Esa1 are a group of closely positioned lysines on the N-terminal tail of histone H4, but, strikingly, full-length histone H4 is acetylated 2000-fold faster than short peptides with the same sequence of amino acids (histone tail peptides) that would normally be found in close proximity to lysine. This indicates that interactions with the histone fold domain of H4 are crucial for high catalytic efficiency and the ability of the enzyme to acetylate four lysine residues within the same H4 tail.
