How do acetylation and phosphorylation affect DNA packaging?

Phosphorylation and acetylation effectively make the DNA more negatively charged by reducing the positive charge of histones, and it loosens the packing of DNA through the disrupted electrostatic interactions between histones and DNA. The less compact chromatin structure facilitates DNA access by mechanisms such as in transcription. Acetylation occurs on histone tail lysines such as H3K9, H3K18, H4K5, H4K8, and H4K12. These sites show that in acetylated regions of the genome, the change on histone tails can be neutralized and thus have a great effect on the chromatin structure. Enzymes that add acetyl groups to histones are known as acetyltransferases. Histone phosphorylation is very site-specific and thus there are fewer sites compared with acetylated sites.