Abstract
A recent publication shows that a simple chemical event, acetylation of lysine 16 on the histone H4 N-terminal tail domain (NTD), completely abolishes the ability of the H4 NTD to mediate the nucleosome–nucleosome interactions involved in chromatin condensation. This result provides novel insight into the molecular mechanism of histone acetylation and also implicates H4 K16acet-dependent changes in chromatin fiber architecture as a central mechanism for generating transcriptionally active genomic domains.