Histone Acetylation

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Histone acetylation is a type of post-translational modification which involves the addition of an acetyl group (COCH3) covalently, from acetyl coenzyme A with the use of enzymes called histone acetyltransferases (HATs)[1]. These enzymes catalyse the addition of an acetyl group on to lysine residues in areas which are usually promoter regions, such as H3 and H4[2]. This type of post-translational modification is reversible, as one enzyme, for example, histone acetyltransferase (HAT), serves to add the acetyl group onto the amino acid and the other enzyme, histone deacetylase complex (HDAC) is to remove the acetyl group added[3]. Therefore, these enzymes are highly specific. As lysine is positively charged and DNA is negatively charged they bind together keeping the structure compact. However, with the addition of a positively charged acetyl group, the structure loosens as it reduces the affinity of the tails for adjacent nucleosomes, thus revealing promoter regions for transcription to occur[4], therefore this regulates the gene expression of the cell[5]. The acetylation of histones is involved in many cellular processes[6].

References

  1. What is Epigenetics. Histone Modifications. Accessed 01/12/16 http://www.whatisepigenetics.com/histone-modifications/
  2. Epigenetics. Histone Modifications. Accessed 01/12/16 http://www.abcam.com/epigenetics/histone-modifications-a-guide
  3. Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts and Peter Walter. (2015) Molecular Biology of The Cell, Sixth Edition, New York: Garland Science. Pg 196-pg 197.
  4. Epigenetics. Histone Modifications. Accessed 01/12/16 http://www.abcam.com/epigenetics/histone-modifications-a-guide
  5. Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts and Peter Walter. (2015) Molecular Biology of The Cell, Sixth Edition, New York: Garland Science.Pg 196-pg 197
  6. What is Epigenetics. Histone Modifications. Accessed 01/12/16 http://www.whatisepigenetics.com/histone-modifications/
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