PROSITE documentation PDOC00089

{PDOC00089}
{PS00094; C5_MTASE_1}
{PS00095; C5_MTASE_2}
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* C-5 cytosine-specific DNA methylases signatures *
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C-5 cytosine-specific DNA methylases (EC 2.1.1.37) (C5 Mtase) are enzymes that
specifically methylate  the  C-5  carbon  of  cytosines  in  DNA [1,2,3]. Such
enzymes are found in the proteins described below.

 - As a component of type II  restriction-modification  systems in prokaryotes
   and some  bacteriophages.    Such enzymes recognize a specific DNA sequence
   where they  methylate  a  cytosine.  In  doing  so,  they  protect DNA from
   cleavage by  type  II restriction enzymes that recognize the same sequence.
   The sequences of a large number of type II C-5 Mtases are known.
 - In vertebrates, there  are  a  number  of  C-5 Mtases  that  methylate  CpG
   dinucleotides. The sequence of the mammalian enzyme is known.

C-5 Mtases share a number of short conserved regions. We selected two of them.
The first  is  centered  around  a  conserved  Pro-Cys  dipeptide in which the
cysteine has  been  shown  [4]  to be involved in the catalytic mechanism;  it
appears to  form a covalent intermediate with the C6 position of cytosine. The
second region is located at the C-terminal extremity in type-II enzymes.

-Consensus pattern: [DENKS]-x-[FLIV]-x(2)-[GSTC]-x-P-C-x-{V}-[FYWLIM]-S
                    [C is the active site residue]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for M.MthtI.
-Other sequence(s) detected in Swiss-Prot: 3.

-Consensus pattern: [RKQGTF]-x(2)-G-N-[SA]-[LIVF]-x-[VIP]-x-[LVMT]-x(3)-
                    [LIVM]-x(3)-[LIVM]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for M.AluI, M.HgaI 1 and 2, and M.HpaII.
-Other sequence(s) detected in Swiss-Prot: 2.

-Note: In the first position of the second pattern, most known Mtases have Arg
 or Lys.

-Expert(s) to contact by email:
           Roberts R.J.; 





roberts@neb.com

           Bickle T.; 





bickle@ubaclu.unibas.ch

           Mugasimangalam R.; 





genotypic@hotmail.com


-Last update: December 2004 / Pattern and text revised.

[ 1] Posfai J., Bhagwat A.S., Roberts R.J.
     "Sequence motifs specific for cytosine methyltransferases."
     Gene 74:261-265(1988).
     PubMed=3248729
[ 2] Kumar S., Cheng X., Klimasauskas S., Mi S., Posfai J., Roberts R.J.,
     Wilson G.G.
     "The DNA (cytosine-5) methyltransferases."
     Nucleic Acids Res. 22:1-10(1994).
     PubMed=8127644
[ 3] Lauster R., Trautner T.A., Noyer-Weidner M.
     "Cytosine-specific type II DNA methyltransferases. A conserved enzyme
     core with variable target-recognizing domains."
     J. Mol. Biol. 206:305-312(1989).
     PubMed=2716049
[ 4] Chen L., MacMillan A.M., Chang W., Ezaz-Nikpay K., Lane W.S.,
     Verdine G.L.
     "Direct identification of the active-site nucleophile in a DNA
     (cytosine-5)-methyltransferase."
     Biochemistry 30:11018-11025(1991).
     PubMed=1932026

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