The beta-globin domain in immature chicken erythrocytes: enhanced solubility is coincident with histone hyperacetylation.

A 60 minute exposure of chicken immature erythrocytes to n-butyrate shifts actively acetylated and deacetylated histones to hypermodified forms. Micrococcal nuclease digestion of nuclei from n-butyrate treated cells and subsequent fractionation of the chromatin releases 40-45% of the adult beta-globin (beta A) nucleohistone into a soluble fraction. This is an eleven fold enrichment over the soluble chromatin from untreated cells (Ferenz and Nelson (1985) Nucleic Acids Res. 13, 1977-1995). The enhanced beta A chromatin solubility and induced histone hyperacetylation are coincident. Removal of n-butyrate from the cell incubation medium allows rapid histone deacetylation and a striking reduction in beta A chromatin solubility. Chromatin from cells incubated in the absence of n-butyrate, or in medium containing 10 mM NaCl or 2% dimethylsulfoxide, does not exhibit histone hyperacetylation, or the acquired solubility of beta A chromatin. We show that the H4 histone co-isolated with the beta A DNA is in a hyperacetylated state and present evidence that the n-butyrate incubation increases the solubility of both coding and noncoding chromatin regions in the beta-globin domain.