Methyl transfer from the ubiquitous S-adenosyl-L-methionine (AdoMet/SAM) to either nitrogen, oxygen or carbon atoms is frequently employed in diverse organisms ranging from bacteria to plants and mammals.
The reaction is catalysed 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.
[1][2] The structure of the Salmonella typhimurium chemotaxis receptor methyltransferase CheR, bound to S-adenosylhomocysteine, has been determined to a resolution of 2.0 Angstrom.
The C-terminal domain has the characteristics of a nucleotide-binding fold, with an insertion of a small anti-parallel beta-sheet subdomain.