Nucleosomal Particles Open as the Histone Core Becomes Hyperacetylated

Abstract

Lymphoblastoid cells [Namalva] grown in the presence of the deacetylase inhibitor butyrate were used to isolate nucleosomal particles in a hyperacetylated state. During a nondenaturing gel electrophoresis, these particles revealed a heterogeneity which is only in part due to the presence of nonhistone proteins. Monomers that are free from histone H1 and high-mobility-group (HMG) proteins 14 and 17 yield a subfractionation according to the degree or core histone acetylation beyond a limiting value of 10 acetyl groups/particle. Hyperacetylation provides particles with low mobilities and a considerable conformational freedom in contrast to HMG protein 14, which locks them in a conformation that has a similar electrophoretic behavior but is more defined.