Reaction: 3 S-adenosyl-L-methionine + a [histone H4]-L-lysine20 = 3 S-adenosyl-L-homocysteine + a [histone H4]-N6,N6,N6-trimethyl-L-lysine20 (overall reaction)
(1a) S-adenosyl-L-methionine + a [histone H4]-L-lysine20 = S-adenosyl-L-homocysteine + a [histone H4]-N6-methyl-L-lysine20
(1b) S-adenosyl-L-methionine + a [histone H4]-N6-methyl-L-lysine20 = S-adenosyl-L-homocysteine + a [histone H4]-N6,N6-dimethyl-L-lysine20
(1c) S-adenosyl-L-methionine + a [histone H4]-N6,N6-dimethyl-L-lysine20 = S-adenosyl-L-homocysteine + a [histone H4]-N6,N6,N6-trimethyl-L-lysine20
Other name(s): SET9 (gene name)
Systematic name: S-adenosyl-L-methionine:[histone H4]-L-lysine20 N6-trimethyltransferase
Comments: The enzyme, characterized from the fission yeast Schizosaccharomyces pombe, catalyses three successive methylations of the L-lysine-20 residue of histone H4 (H4K20), forming the trimethylated form. The methylation of this site is apparently not involved in the regulation of gene expression or heterochromatin function but participates in DNA damage response. cf. EC 2.1.1.361, [histone H4]-lysine20 N-methyltransferase, and EC 2.1.1.362, [histone H4]-N-methyl-L-lysine20 N-methyltransferase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc PDB, CAS registry number:
References:
1. Sanders, S.L., Portoso, M., Mata, J., Bahler, J., Allshire, R.C. and Kouzarides, T. Methylation of histone H4 lysine 20 controls recruitment of Crb2 to sites of DNA damage. Cell 119 (2004) 603-614. [PMID: 15550243]