DNA-Methyltransferase

DNA methyltransferases, also called DNA MTase, are enzymes that transfer methyl groups to nucleobases of DNA. The reaction catalyzed by these enzymes DNA methylation has a variety of biological functions. In bacteria, they are used, among other things bacteria to methylate their own DNA to distinguish as foreign DNA and can own DNA. Use all known DNA methyltransferases S- Andenosyl -methionine (SAM ) as a methyl group donor.

Classification

EC classification

DNA MTase can according to the chemical reactions which they catalyze, be divided into three groups:

• M6A - production of N6 -methyladenine ( EC 2.1.1.72 )
• M4C - generating N4- methylcytosine ( EC 2.1.1.113 )
• M5C - production of C5 -methylcytosine ( EC 2.1.1.37 )

De novo and maintenance ( servicing ) DNA MTases

De novo methyltransferases recognize specific sites in the DNA, which allow them to methylate cytosine de novo. This is particularly important in early embryonic development, since it is a methylation pattern is established (see also imprinting ).

Maintenance methyltransferases add methyl groups to the DNA in such places, where on a DNA strand a methyl group already exists. Thereby, the methylation pattern which was established once by embryonic de novo MTase obtained.