ACETYLATION OF HISTONE H2A.H2B DIMERS FACILITATES TRANSCRIPTION

Histone-DNA templates for bacteriophage T7 RNA polymerase were assembl ed from a plasmid containing a promoter and a terminator for T7 RNA po lymerase, intact (H3.H4)(2) tetramers, and either untreated or chemica lly acetylated H2A.H2B dimers. The nucleosomal particles containing ac etylated H2A.H2B dimers protect 145 base pairs of DNA against micrococ cal nuclease digestion and prevent the reaction with psoralen of 80 to 145 DNA base pairs. The inhibition of transcriptional initiation caus ed by the association of DNA with intact core histone octamers decreas es 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 dea cetylation of their lysine residues. (C) 1995 Academic Press, Inc.