Reaction: S-adenosyl-L-methionine + DNA cytosine = S-adenosyl-L-homocysteine + DNA N4-methylcytosine
Other name(s): modification methylase; restriction-modification system; DNA[cytosine-N4]methyltransferase; m4C-forming MTase
Systematic name: S-adenosyl-L-methionine:DNA-cytosine N4-methyltransferase
Comments: This is a large group of enzymes, most of which, with enzymes of similar site specificity listed as EC 3.1.21.3 (type 1 site-specific deoxyribonuclease), EC 3.1.21.4 (type II site-specific deoxyribonuclease) or EC 3.1.21.5 (type III site-specific deoxyribonuclease), form so-called 'restriction-modification systems'. A complete listing of all of these enzymes has been produced by R.J. Roberts and is available on-line at http://rebase.neb.com/rebase/rebase.html.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 169592-50-1
References:
1. Kessler, C. and Manta, V. Specificity of restriction endonucleases and DNA modification methyltransferases. A review (Edition 3). Gene 92 (1990) 1-248. [PMID: 2172084]
2. Klimasauskas, S., Timinskas, A., Menkevicius, S., Butkiene, D., Butkus, V. and Janulaitis, A. Sequence motifs characteristic of DNA[cytosine-N4]methyltransferases: similarity to adenine and cytosine-C5 DNA-methylases. Nucleic Acids Res. 17 (1989) 9823-9832. [PMID: 2690010]
3. Roberts, R.J. Restriction enzymes and their isoschizomers. Nucleic Acids Res. 18 (1990) 2331-2365. [PMID: 2159140]
4. Yuan, R. Structure and mechanism of multifunctional restriction endonucleases. Annu. Rev. Biochem. 50 (1981) 285-319. [PMID: 6267988]