EC 2.1.1.366     
Accepted name: [histone H3]-N6,N6-dimethyl-lysine9 N-methyltransferase
Reaction: S-adenosyl-L-methionine + a [histone H3]-N6,N6-dimethyl-L-lysine9 = S-adenosyl-L-homocysteine + a [histone H3]-N6,N6,N6-trimethyl-L-lysine9
Other name(s): KMT1E (gene name); SETDB1 (gene name); KIAA0067 (gene name)
Systematic name: S-adenosyl-L-methionine:[histone H3]-N6,N6-dimethyl-L-lysine9 N6-methyltransferase
Comments: The enzyme methylates only dimethylated lysine9 of histone H3 (H3K9), forming the trimethylated form. This modification influences the binding of chromatin-associated proteins. In general, the methylation of H3K9 leads to transcriptional repression of the affected target genes. The enzyme is highly upregulated in Huntington disease patients. cf. EC 2.1.1.367, [histone H3]-lysine9 N-methyltransferase, and EC 2.1.1.368, [histone H3]-lysine9 N-dimethyltransferase, and EC 2.1.1.355, [histone H3]-lysine9 N-trimethyltransferase.
References:
1.  Yang, L., Xia, L., Wu, D.Y., Wang, H., Chansky, H.A., Schubach, W.H., Hickstein, D.D. and Zhang, Y. Molecular cloning of ESET, a novel histone H3-specific methyltransferase that interacts with ERG transcription factor. Oncogene 21 (2002) 148–152. [PMID: 11791185]
2.  Wang, H., An, W., Cao, R., Xia, L., Erdjument-Bromage, H., Chatton, B., Tempst, P., Roeder, R.G. and Zhang, Y. mAM facilitates conversion by ESET of dimethyl to trimethyl lysine 9 of histone H3 to cause transcriptional repression. Mol. Cell 12 (2003) 475–487. [PMID: 14536086]
3.  Pinheiro, I., Margueron, R., Shukeir, N., Eisold, M., Fritzsch, C., Richter, F.M., Mittler, G., Genoud, C., Goyama, S., Kurokawa, M., Son, J., Reinberg, D., Lachner, M. and Jenuwein, T. Prdm3 and Prdm16 are H3K9me1 methyltransferases required for mammalian heterochromatin integrity. Cell 150 (2012) 948–960. [PMID: 22939622]
[EC 2.1.1.366 created 2020]