|PROSITE documentation PDOC00087|
N-6 adenine-specific DNA methylases (EC 18.104.22.168) (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.Note:
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:
December 2004 / Pattern and text revised.
PROSITE method (with tools and information) covered by this documentation:
|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).|
|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.|
|Title||Evolution of type II DNA methyltransferases. A gene duplication model.|
|Source||J. Mol. Biol. 206:313-321(1989).|
|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.|