EzCatDB: D00080

DB codeD00080
RLCP classification3.747.29000.21
CATH domainDomain 13.40.50.150Catalytic domain
Domain 23.90.220.10
E.C.2.1.1.72
CSA2adm
MACiEM0046

CATH domainRelated DB codes (homologues)
3.40.50.150S00637,S00639,S00262,S00261,S00291,S00412,D00075,D00076,D00079,D00082,D00083,D00823

Enzyme Name
Swiss-protKEGG

P14385
Protein nameModification methylase TaqIsite-specific DNA-methyltransferase (adenine-specific)
modification methylase
restriction-modification system
SynonymsM.TaqI
EC 2.1.1.72
Adenine-specific methyltransferase TaqI


Swiss-prot:Accession NumberP14385
Entry nameMTTA_THEAQ
ActivityS-adenosyl-L-methionine + DNA adenine = S- adenosyl-L-homocysteine + DNA 6-methylaminopurine.
Subunit
Subcellular location
Cofactor


SubstratesProducts
KEGG-idC00019C00821C00021C03391
CompoundS-Adenosyl-L-methionineDNA adenineS-Adenosyl-L-homocysteineDNA 6-methylaminopurine
Typeamino acids,amine group,nucleoside,sulfonium ionamine group,nucleic acidsamino acids,amine group,nucleoside,sulfide groupamine group,nucleic acids
1admA01Bound:SAMUnboundUnboundUnbound
1admB01Bound:SAMUnboundUnboundUnbound
1aqiA01UnboundUnboundBound:SAHUnbound
1aqiB01UnboundUnboundBound:SAHUnbound
1aqjA01Analogue:SFGUnboundUnboundUnbound
1aqjB01Analogue:SFGUnboundUnboundUnbound
1g38A01UnboundBound:_DA 606(chain B)Analogue:NEAUnbound
1g38D01UnboundBound:_DA 606(chain E)Analogue:NEAUnbound
2admA01Bound:SAMUnboundUnboundUnbound
2admB01Bound:SAMUnboundUnboundUnbound
1admA02UnboundUnboundUnboundUnbound
1admB02UnboundUnboundUnboundUnbound
1aqiA02UnboundUnboundUnboundUnbound
1aqiB02UnboundUnboundUnboundUnbound
1aqjA02UnboundUnboundUnboundUnbound
1aqjB02UnboundUnboundUnboundUnbound
1g38A02UnboundUnboundUnboundUnbound
1g38D02UnboundUnboundUnboundUnbound
2admA02UnboundUnboundUnboundUnbound
2admB02UnboundUnboundUnboundUnbound

Active-site residues
pdbCatalytic residuesMain-chain involved in catalysis
1admA01ASN 105;TYR 108
PRO 106
1admB01ASN 105;TYR 108
PRO 106
1aqiA01ASN 105;TYR 108
PRO 106
1aqiB01ASN 105;TYR 108
PRO 106
1aqjA01ASN 105;TYR 108
PRO 106
1aqjB01ASN 105;TYR 108
PRO 106
1g38A01ASN 105;TYR 108
PRO 106
1g38D01ASN 105;TYR 108
PRO 106
2admA01

2admB01

1admA02

1admB02

1aqiA02

1aqiB02

1aqjA02

1aqjB02

1g38A02

1g38D02

2admA02

2admB02


References for Catalytic Mechanism
ReferencesSectionsNo. of steps in catalysis
[2]p.134
[5]p.63
[6]p.124

references
[1]
PubMed ID8070417
JournalEMBO J
Year1994
Volume13(16)
Pages3902-8
AuthorsWillcock DF, Dryden DT, Murray NE
TitleA mutational analysis of the two motifs common to adenine methyltransferases.
[2]
PubMed ID7971991
JournalProc Natl Acad Sci U S A
Year1994
Volume91(23)
Pages10957-61
AuthorsLabahn J, Granzin J, Schluckebier G, Robinson DP, Jack WE, Schildkraut I, Saenger W
TitleThree-dimensional structure of the adenine-specific DNA methyltransferase M.Taq I in complex with the cofactor S-adenosylmethionine.
Related PDB1adm
Related Swiss-protP14385
[3]
PubMed ID7607476
JournalGene
Year1995
Volume157(1-2)
Pages131-4
AuthorsSchluckebier G, Labahn J, Granzin J, Schildkraut I, Saenger W
TitleA model for DNA binding and enzyme action derived from crystallographic studies of the TaqI N6-adenine-methyltransferase.
[4]
PubMed ID7897657
JournalJ Mol Biol
Year1995
Volume247(1)
Pages16-20
AuthorsSchluckebier G, O'Gara M, Saenger W, Cheng X
TitleUniversal catalytic domain structure of AdoMet-dependent methyltransferases.
[5]
PubMed ID8995524
JournalJ Mol Biol
Year1997
Volume265(1)
Pages56-67
AuthorsSchluckebier G, Kozak M, Bleimling N, Weinhold E, Saenger W
TitleDifferential binding of S-adenosylmethionine S-adenosylhomocysteine and Sinefungin to the adenine-specific DNA methyltransferase M.TaqI.
Related PDB1aqi,1aqj,2adm
[6]
PubMed ID11175899
JournalNat Struct Biol
Year2001
Volume8(2)
Pages121-5
AuthorsGoedecke K, Pignot M, Goody RS, Scheidig AJ, Weinhold E
TitleStructure of the N6-adenine DNA methyltransferase M.TaqI in complex with DNA and a cofactor analog.
Related PDB1g38

comments
According to the literature [5] & [6], this enzyme catalyzes a direct methyl transfer to the acceptor amine group, adenine N6. Although acceptor groups are usually activated by general bases, the activation mechanism of this enzyme and the role of general base are very unique, according to the literature [6].
(1) The sidechain of Asn105 and mainchain carbonyl oxygen of Pro106 seem to activate and enhance the nucleophilicity of the acceptor amine group, adenine N6, by increasing the electron density of the acceptor group, and by assisting its hybridization change from sp2 towards sp3.
(2) Thus, the acceptor group would be in a position for an inline attack on the methyl group of another substrate, SAM.
(3) The resulting tetrahedral methyl-ammonium group intermediate would be stabilized by the hydrogen bonds to Asn105 and Pro106. Moreover, the positively charged intermediate and transtion state could be stabilized by cation-pi interactions with the electron-rich aromatic ring of Tyr108.
(4) As the pKa of the methyl-ammonium group reduces dramatically, the sidechain of Asn105 and the mainchain of Pro106 could deprotonate the methyl-ammonium intermediate as general bases, which would complete the catalytic reaction.

createdupdated
2002-08-132009-02-26


Copyright: Nozomi Nagano, JST & CBRC-AIST
Funded by PRESTO/Japan Science and Technology Corporation (JST) (December 2001 - November 2004)
Funded by Grant-in-Aid for Publication of Scientific Research Results/Japan Society for the Promotion of Science (JSPS) (April 2005 - March 2006)
Funded by Grant-in-Aid for Scientific Research (B)/Japan Society for the Promotion of Science (JSPS) (April 2005 - March 2008)
Funded by BIRD/Japan Science and Technology Corporation (JST) (September 2005 - September 2010)
Funded by BIRD/Japan Science and Technology Corporation (JST) (October 2007 - September 2010)
Funded by Grant-in-Aid for Publication of Scientific Research Results/Japan Society for the Promotion of Science (JSPS) (April 2011 - March 2012)

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