Dynamically acetylated histones of chicken erythrocytes are selectively methylated.

The relationship between histone acetylation and methylation in chicken immature erythrocytes was investigated. Previous studies have shown that transcriptionally active/competent gene-enriched chromatin fragments are enriched in newly methylated histones H3 and H4. Moreover, newly methylated histone H4 is hyperacetylated. Here, we show that dynamically acetylated histone H4 is selectively engaged in ongoing methylation. While sodium butyrate (an inhibitor of histone deacetylase) does not inhibit ongoing histone methylation, it does affect the acetylation state of newly methylated histone H4 when chicken immature erythrocytes are incubated in its presence or absence. Only one rate of acetylation of labelled newly methylated unacetylated histone H4 with a t1/2 of 8 min is observed. Previous studies have shown that the solubility of transcriptionally active/competent gene chromatin fragments in 0.15 M-NaCl is dependent upon the level of acetylated histone species, with induction of hyperacetylation increasing the solubility of this gene chromatin. Here, we show that the low salt solubility of chromatin fragments associated with newly methylated histones H3 and H4 is also dependent upon the level of acetylated histones. These results provide further support for the hypothesis that histones participating in ongoing methylation are associated with transcriptionally active/competent chromatin and suggest that the processes of histone H4 methylation and dynamic acetylation are partially coupled in terminally differentiated erythrocytes.