Decreased acetylation of associated histones

• Acetylation is the process whereby an acetyl group is transferred to a molecule. Therefore, the reverse process (deacetylation) involves removing a acetyl group from a molecule.
• When histones are acetylated, the group donating the acetyl group is the acetyl coenzyme A from the Link Reaction.
• Decreased acetylation increases the positive charges on histones and therefore increases their attraction to the phosphate groups on DNA. This makes the DNA-histone association stronger, so the DNA is not accessible by transcription factors. The transcription factors cannot initiate mRNA production from DNA, therefore the gene is switched off.