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#histone acetylation

2 public questions tagged with this topic.

Regulation of chromatin structure

Which residue is commonly acetylated in histones?

Lysine residues in histone tails are primary targets for acetylation because their ε-amino group carries positive charge at physiological pH and can accept acetyl from acetyl-CoA via HAT enzymes such as p300/CBP and Gcn5. Acetylation neutralizes charge, disrupts salt bridges with DNA phosphate, increases tail flexibility and creates docking sites for bromodomains. Arginine undergoes methylation, serine and threonine undergo phosphorylation, while lysine uniquely combines charge modulation with reader recruitment. Frequent sites include H3K9, K14, K27 and H4K5, K8, K12, K16, linking metabolic acetyl-CoA availability to gene activation status.

Ref: Berg et al., Biochemistry, 9th ed., Chapter 30: Histone Acetylation at Lysine Residues

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Eukaryotic chromatin and chromosome

Histone acetylation causes:

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.

Ref: Allfrey et al., 1964; Alberts et al., Molecular Biology of the Cell, Chapter 4: Histone Acetylation Causes Relaxation

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