PROSITE documentation PDOC00087

N-6 Adenine-specific DNA methylases signature


N-6 adenine-specific DNA methylases (EC (A-Mtase) are enzymes that specifically methylate the amino group at the C-6 position of adenines in DNA. Such enzymes are found in the three existing types of bacterial restriction-modification systems (in type I system the A-Mtase is the product of the hsdM gene, and in type III it is the product of the mod gene). All of these enzymes recognize a specific sequence in DNA and methylate an adenine in that sequence.

It has been shown [1,2,3,4] that A-Mtases contain a conserved motif Asp/Asn-Pro-Pro-Tyr/Phe in their N-terminal section, this conserved region could be involved in substrate binding or in the catalytic activity. We have derived a pattern from that motif.


N-4 cytosine-specific DNA methylases, which are probably enzymatically related to A-Mtases, also include a conserved Pro-Pro dipeptide but the residues around them are sufficiently different to allow the derivation of a pattern specific to these enzymes.

Expert(s) to contact by email:

Roberts R.J.
Bickle T.

Last update:

December 2004 / Pattern and text revised.

Technical section


N6_MTASE, PS00092; N-6 Adenine-specific DNA methylases signature  (PATTERN)


1AuthorsLoenen W.A.M., Daniel A.S., Braymer H.D., Murray N.E.
TitleOrganization and sequence of the hsd genes of Escherichia coli K-12.
SourceJ. Mol. Biol. 198:159-170(1987).
PubMed ID3323532

2AuthorsNarva K.E., Van Etten J.L., Slatko B.E., Benner J.S.
SourceGene 74:253-259(1988).
PubMed ID3248728

3AuthorsLauster R.
TitleEvolution of type II DNA methyltransferases. A gene duplication model.
SourceJ. Mol. Biol. 206:313-321(1989).
PubMed ID2541254

4AuthorsTiminskas A., Butkus V., Janulaitis A.
SourceGene 157:3-11(1995).
PubMed ID7607512

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