Histone phosphorylation. Model for the interplay of histone phosphorylation events and the NuA4 HAT complex during the repair of DNA double-strand breaks. Appearance of a double-strand break is depicted in the context of chromatin. The proposed access, repair, and restore steps of chromatin modification during DNA repair are indicated. Phosphorylation of H2A(X), recruitment of NuA4, and chromatin acetylation are early events, while chromatin deacetylation and H4 phosphorylation are proposed to occur at the late stage of chromatin reassembly after DNA damage is repaired. In this situation, phosphorylation of H4 blocks local reacetylation by NuA4. Not altered. CC. Regulation of NuA4 Histone Acetyltransferase Activity inTranscription and DNA Repair by Phosphorylation of Histone H4 Rhea T. Utley, Nicolas Lacoste, Olivier Jobin-Robitaille, Stephane Allard, and Jacques Cote