Acetylation of histone H2A.H2B dimers facilitates transcription

Histone-DNA templates for bacteriophage T7 RNA polymerase were assembled from a plasmid containing a promoter and a terminator for T7 RNA polymerase, intact (H3.H4)2 tetramers, and either untreated or chemically acetylated H2A.H2B dimers. The nucleosomal particles containing acetylated H2A.H2B dimers protect 145 base pairs of DNA against micrococcal nuclease digestion and prevent the reaction with psoralen of 80 to 145 DNA base pairs. The inhibition of transcriptional initiation caused by the association of DNA with intact core histone octamers decreases significantly when the histone octamers contain acetylated H2A.H2B dimers. These results suggest a role for H2A.H2B dimers in the control of transcription, which might be mediated through acetylation and deacetylation of their lysine residues.