InterPro domain: IPR013216

Methyl transfer from the ubiquitous S-adenosyl-L-methionine (SAM) to either nitrogen, oxygen or carbon atoms is frequently employed in diverse organisms ranging from bacteria to plants and mammals. The reaction is catalyzed by methyltransferases (Mtases) and modifies DNA, RNA, proteins and small molecules, such as catechol for regulatory purposes. The various aspects of the role of DNA methylation in prokaryotic restriction-modification systems and in a number of cellular processes in eukaryotes including gene regulation and differentiation is well documented.

This entry represents a methyltransferase domain found in a large variety of SAM-dependent methyltransferases including, but not limited to:

• Arsenite methyltransferase ( 2.1.1.137 ) which converts arsenical compounds to their methylated forms [ 1 ]
• Biotin synthesis protein bioC, which is involved in the early stages of biotin biosyntheis [ 2 ]
• Arginine N-methyltransferase 1, an arginine-methylating enzyme which acts on residues present in a glycine and argine-rich domain and can methylate histones [ 3 ]
• Hexaprenyldihydroxybenzoate methyltransferase ( 2.1.1.114 ), a mitochodrial enzyme involved in ubiquinone biosynthesis [ 4 ]
• A probable cobalt-precorrin-6Y C(15)-methyltransferase thought to be involved in adenosylcobalamin biosynthesis [ 5 ]
• Sterol 24-C-methyltransferase ( 2.1.1.41 ), shown to participate in ergosterol biosynthesis [ 6 ]
• 3-demethylubiquinone-9 3-methyltransferase ( 2.1.1.64 ) involved in ubiquinone biosynthesis [ 7 ]

Structural studies show that this domain forms the Rossman-like alpha-beta fold typical of SAM-dependent methyltransferases [ 8 , 9 , 10 ].

1. A novel S-adenosyl-L-methionine:arsenic(III) methyltransferase from rat liver cytosol. J. Biol. Chem. 277, 10795-803
2. Molecular cloning and nucleotide sequencing of bioF (7-keto-8-amino pelargonic acid synthetase), bioC and bioD (dethiobiotin synthetase) genes of Erwinia herbicola. Biochem. Mol. Biol. Int. 41, 311-5
3. Arginine N-methyltransferase 1 is required for early postimplantation mouse development, but cells deficient in the enzyme are viable. Mol. Cell. Biol. 20, 4859-69
4. Yeast and rat Coq3 and Escherichia coli UbiG polypeptides catalyze both O-methyltransferase steps in coenzyme Q biosynthesis. J. Biol. Chem. 274, 21665-72
5. Characterization of the cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium. J. Bacteriol. 175, 3303-16
6. Sequencing, disruption, and characterization of the Candida albicans sterol methyltransferase (ERG6) gene: drug susceptibility studies in erg6 mutants. Antimicrob. Agents Chemother. 42, 1160-7
7. Isolation and characterization of Escherichia coli mutants affected in aerobic respiration: the cloning and nucleotide sequence of ubiG. Identification of an S-adenosylmethionine-binding motif in protein, RNA, and small-molecule methyltransferases. J. Gen. Microbiol. 138, 2101-12
8. Structure of the predominant protein arginine methyltransferase PRMT1 and analysis of its binding to substrate peptides. Structure 11, 509-20
9. Crystal structure of RlmAI: implications for understanding the 23S rRNA G745/G748-methylation at the macrolide antibiotic-binding site. Proc. Natl. Acad. Sci. U.S.A. 101, 4041-6
10. The crystal structure of MT0146/CbiT suggests that the putative precorrin-8w decarboxylase is a methyltransferase. Structure 10, 1475-87