Epigenetic Writers and Erasers of Histones H2A, H2B, and H4 Pathway

an Overview of Epigenetics Writers and Erasers

Epigenetic writers are enzymes that add chemical groups such methyl, acetyl, sumo and phosphates on histones via processes including methylation, acetylation, sumolyation and phosphorylation respectively. Epigenetic erasers are enzymes that remove the above chemical groups from histones via processes including demethylation, deacetylation, desumolyation and dephosphorylation respectively. Writers and erasers affect their activity on various amino acids residues denoted by letters and a number to show the position of the amino acid of that type. Both groups of enzymes are very much involved in post translation modifications (PTMs). PTMs are essential for proper gene expression, genome organization, cell division and DNA damage response. Histones are packaging proteins elements of DNA that compose a chromatin. Examples of histone proteins include histone 2A (H2A) and 2B (H2B), histone 3 (H3) and histone 4 (H4).

This is done based on a particular amino acid residue. Each residue has its writers and erasers and some have similar writers and erasers. The enzymes are professionally written in abbreviations denoting their function and or their area of activity. They include the following: first serine residue (S1) is phosphorylated by MSK1 and PKC which are kinases. Third arginine residue (R3) is dimethylated assymetrically by PRMTG which is a methyltransferase. Fifth lysine residue (K5) is acetylates by the following acetyltransferase; HAT1, CBP/KAT3A, p300/KAT3B and TIP60/KAT5. Ninth lysine residue (K9) is acetylated by HDAC5 which is an acetyltransferase.

The fifth lysine residue (K5) is acetylated by CBP/KAT3A and p300/KAT3B which are acetyltransferases. Eleventh arginine residue is dimethylated asymmetrically by PRMT1 and PRMT6 which are methyltransferases. Twelfth lysine residue (K12) is acetylated by CBP/KAT3A and p300/KAT3B. The fourteenth serine residue (S14) is phosphorylated by MST1 which is a Kinase. Fifteenth lysine residue (K15) is acetylated by CBP/KAT3A and p300/KAT3B. Twentieth, twenty third and twenty fourth lysine residues are acetylated by CBP/KAT3A and p300/KAT3B. Twenty ninth arginine residue (R29) is dimethylated asymmetrically by PRMT1 and PRMT6 which are methyltransferases.

he first serine residue (S1) is phosphorylated by CKll which is a kinase. Third arginine residue (R3) is dimethylated asymmetrically by PRMT1 and PRMT5 which are methyltransferases. Fifth lysine residue (K5) is acetylated by the following acetyltransferases; HAT1, GCN5L2/KAT2A, CBP/KAT3A, p300/KAT3B, TIP60/KAT5 and MYST/KAT7 which are all acetyltransferases. Eighth lysine residue (K8)is acetylated by ELP3 and the same acetyltransferases as K5 apart from HAT1. Twelfth lysine residue (K12) is acetylated by the same acetyltransferases as K5. Sixteenth lysine residue (K16) is acetylated by SirT1, SirT2, SirT6 the same acetyltransferases as K5 apart from HAT1. Twentieth lysine residue (K20) is acetylated by the same acetyltransferases as K16. K20 is methylated by SET8/KMT5A which are methyltransferases. NSD1/KMT3B and NSD2/KMT3G are methyltransferases that methylate or dimethylate K20. SUV420H1/KMT5B and SUV420H1/KMT5C are methyltransferases that dimethylate or trimethylate K20.