Fig. 7.

We propose a speculative molecular level explanation of the H4 tail acetylation induced chromatin fiber decompaction. A schematic drawing of the polynucleosomal array is shown, with nucleosomes represented as red cylinder and H4 histone tails as gray lines. Only the N terminals of the H4 tails are shown for clarity purposes. The yellow sphere at the end of the H4 tail indicates the N-terminal region. We hypothesize that upon acetylation the H4 tails undergo collapse and, subsequently, their binding to adjacent nucleosomes is compromised, which results in weakening of the effective inter nucleosomal contacts.