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N-6 adenine-specific DNA methylases (EC 2.1.1.72) (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.

Roberts R.J.
Bickle T.

December 2004 / Pattern and text revised.

PROSITE method (with tools and information) covered by this documentation:

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

Consensus pattern: [LIVMAC]-[LIVFYWA]-{DYP}-[DN]-P-P-[FYW] Sequences known to belong to this class detected by the pattern: ALL, except for m.HhaII where the second Pro is replaced by Gln and in m.HindIII where that same Pro is replaced by Tyr Other sequence(s) detected in Swiss-Prot: 33 different proteins that are most probably not A-Mtases, and three hypothetical Escherichia coli proteins that could be A-Mtases.

• Retrieve an alignment of Swiss-Prot true positive hits:   Clustal format, color, condensed view  / Clustal format, color  / Clustal format, plain text  / Fasta format • Retrieve the sequence logo from the alignment • Taxonomic tree view of all Swiss-Prot/TrEMBL entries matching PS00092 • Retrieve a list of all Swiss-Prot/TrEMBL entries matching PS00092 • Scan Swiss-Prot/TrEMBL entries against PS00092 • view ligand binding statistics

Matching PDB structures: 1AQI 1AQJ 1EG2 1G38 ... [ALL]

1	Authors	Loenen W.A.M., Daniel A.S., Braymer H.D., Murray N.E.
	Title	Organization and sequence of the hsd genes of Escherichia coli K-12.
	Source	J. Mol. Biol. 198:159-170(1987).
	PubMed ID	3323532

2	Authors	Narva K.E., Van Etten J.L., Slatko B.E., Benner J.S.
	Title	The amino acid sequence of the eukaryotic DNA [N6-adenine]methyltransferase, M.CviBIII, has regions of similarity with the prokaryotic isoschizomer M.TaqI and other DNA [N6-adenine] methyltransferases.
	Source	Gene 74:253-259(1988).
	PubMed ID	3248728

3	Authors	Lauster R.
	Title	Evolution of type II DNA methyltransferases. A gene duplication model.
	Source	J. Mol. Biol. 206:313-321(1989).
	PubMed ID	2541254

4	Authors	Timinskas A., Butkus V., Janulaitis A.
	Title	Sequence motifs characteristic for DNA [cytosine-N4] and DNA [adenine-N6] methyltransferases. Classification of all DNA methyltransferases.
	Source	Gene 157:3-11(1995).
	PubMed ID	7607512

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