Chapter 2 - Histone Acetylation During Chromatin Replication and Nucleosome Assembly

Abstract

The biochemical and genetic data indicate that the reversible acetylation of nascent H4 is dispensable for histone deposition and physiological nucleosome alignment. Of course, the genetic evidence obtained from yeast may in part reflect the peculiarities of this system, while the ability of acetylated H3 to substitute for H4Ac2 remains untested. These matters should be fertile areas for future research. Approaches for addressing these problems might include a conditional mutant for HATB, or a specific inhibitor of this enzyme. In vitro assembly systems, in which the acetylation of H4 can be manipulated, should also prove valuable. Given that heightened DNaseI sensitivity is a feature of acetylated chromatin in general, it is perhaps ironic that the only clearly identified assembly-related effect of histone acetylation is the prolonged DNaseI sensitivity of chromatin replicated in the presence of butyrate. Whether this represents an actual role for acetylation during nucleosome assembly in vivo, it does underscore the importance of timely deacetylation in the proper and complete formation of chromatin.