Practice question

Acetylation of epsilon amino groups on histone tail lysines by HAT complexes like p300, CBP and GCN5 neutralizes positive charge, weakening interaction with negatively charged phosphate backbone and loosening nucleosome wrapping around DNA gyres. Bromodomain-containing proteins specifically recognize acetyllysine and recruit ATP remodelers and polymerase associated factors. Acetylation at H4 K16 directly disrupts interaction with acidic patch on neighboring H2A-H2B dimer required for 30 nanometer fiber formation. Consequently acetylation produces open relaxed chromatin permissive for transcription, replication and repair, opposing condensation and methylation-driven silencing pathways effectively.