{PDOC00088}
{PS00093; N4_MTASE}
{BEGIN}
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* N-4 cytosine-specific DNA methylases signature *
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N-4 cytosine-specific DNA methylases (EC 2.1.1.113) [1,2,3]  are  enzymes that
specifically  methylate  the  amino  group at the C-4 position of cytosines in
DNA. Such enzymes are found as components of type II  restriction-modification
systems in prokaryotes.  Such enzymes recognize a specific sequence in DNA and
methylate a cytosine in that sequence.    By this action they protect DNA from
cleavage by type II restriction enzymes that recognize the same sequence.

Type II N-4 Mtases seem to be  structurally  and  enzymatically related to N-6
adenine-specific DNA methylases.  Like the N-6 Mtases they contain a conserved
Pro-Pro-Tyr/Phe region,  but the N- and C-terminal contexts of this region are
sufficiently different  to derive a consensus pattern specific to this type of
enzymes.

-Consensus pattern: [LIVMF]-T-S-P-P-[FY]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: 5.

-Expert(s) to contact by email:
           Roberts R.J.; roberts@neb.com
           Bickle T.; bickle@ubaclu.unibas.ch

-Last update: November 1997 / Text revised.

[ 1] Tao T., Walter J., Brennan K.J., Cotterman M.M., Blumenthal R.M.
     "Sequence, internal homology and high-level expression of the gene for
     a DNA-(cytosine N4)-methyltransferase, M.Pvu II."
     Nucleic Acids Res. 17:4161-4175(1989).
     PubMed=2662138
[ 2] Klimasauskas S., Timinskas A., Menkevicius S., Butkiene D., Butkus V.,
     Janulaitis A.
     "Sequence motifs characteristic of DNA[cytosine-N4]methyltransferases:
     similarity to adenine and cytosine-C5 DNA-methylases."
     Nucleic Acids Res. 17:9823-9832(1989).
     PubMed=2690010
[ 3] Timinskas A., Butkus V., Janulaitis A.
     "Sequence motifs characteristic for DNA [cytosine-N4] and DNA
     [adenine-N6] methyltransferases. Classification of all DNA
     methyltransferases."
     Gene 157:3-11(1995).
     PubMed=7607512

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