DB code: D00080

RLCP classification 3.747.29000.21 : Transfer
CATH domain 3.40.50.150 : Rossmann fold Catalytic domain
3.90.220.10 : Adenine-n6-DNA-methyltransferase TaqI; Chain A, domain 2
E.C. 2.1.1.72
CSA 2adm
M-CSA 2adm
MACiE M0046

CATH domain Related DB codes (homologues)
3.40.50.150 : Rossmann fold S00637 S00639 S00262 S00261 S00291 S00412 D00075 D00076 D00079 D00082 D00083 D00823

Uniprot Enzyme Name
UniprotKB Protein name Synonyms Pfam
P14385 Modification methylase TaqI
M.TaqI
EC 2.1.1.72
Adenine-specific methyltransferase TaqI
PF12950 (TaqI_C)
[Graphical View]

KEGG enzyme name
site-specific DNA-methyltransferase (adenine-specific)
modification methylase
restriction-modification system

UniprotKB: Accession Number Entry name Activity Subunit Subcellular location Cofactor
P14385 MTTA_THEAQ S-adenosyl-L-methionine + DNA adenine = S- adenosyl-L-homocysteine + DNA 6-methylaminopurine.

KEGG Pathways
Map code Pathways E.C.

Compound table
Substrates Products Intermediates
KEGG-id C00019 C00821 C00021 C03391
E.C.
Compound S-Adenosyl-L-methionine DNA adenine S-Adenosyl-L-homocysteine DNA 6-methylaminopurine
Type amino acids,amine group,nucleoside,sulfonium ion amine group,nucleic acids amino acids,amine group,nucleoside,sulfide group amine group,nucleic acids
ChEBI 67040
57856
16680
PubChem 34755
439155
25246222
1admA01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Bound:SAM Unbound Unbound Unbound
1admB01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Bound:SAM Unbound Unbound Unbound
1aqiA01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Bound:SAH Unbound
1aqiB01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Bound:SAH Unbound
1aqjA01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Analogue:SFG Unbound Unbound Unbound
1aqjB01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Analogue:SFG Unbound Unbound Unbound
1g38A01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Bound:_DA_606(chain B) Analogue:NEA Unbound
1g38D01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Bound:_DA_606(chain E) Analogue:NEA Unbound
2admA01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Bound:SAM Unbound Unbound Unbound
2admB01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Bound:SAM Unbound Unbound Unbound
1admA02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound
1admB02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound
1aqiA02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound
1aqiB02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound
1aqjA02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound
1aqjB02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound
1g38A02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound
1g38D02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound
2admA02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound
2admB02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound

Reference for Active-site residues
resource references E.C.

Active-site residues
PDB Catalytic residues Cofactor-binding residues Modified residues Main-chain involved in catalysis Comment
1admA01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain ASN 105;TYR 108 PRO 106
1admB01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain ASN 105;TYR 108 PRO 106
1aqiA01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain ASN 105;TYR 108 PRO 106
1aqiB01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain ASN 105;TYR 108 PRO 106
1aqjA01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain ASN 105;TYR 108 PRO 106
1aqjB01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain ASN 105;TYR 108 PRO 106
1g38A01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain ASN 105;TYR 108 PRO 106
1g38D01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain ASN 105;TYR 108 PRO 106
2admA01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
2admB01 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
1admA02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
1admB02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
1aqiA02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
1aqiB02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
1aqjA02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
1aqjB02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
1g38A02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
1g38D02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
2admA02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain
2admB02 Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain

References for Catalytic Mechanism
References Sections No. of steps in catalysis
[2]
p.134
[5]
p.63
[6]
p.124

References
[1]
Resource
Comments
Medline ID
PubMed ID 8070417
Journal EMBO J
Year 1994
Volume 13(16)
Pages 3902-8
Authors Willcock DF, Dryden DT, Murray NE
Title A mutational analysis of the two motifs common to adenine methyltransferases.
Related PDB
Related UniProtKB
[2]
Resource
Comments
Medline ID
PubMed ID 7971991
Journal Proc Natl Acad Sci U S A
Year 1994
Volume 91(23)
Pages 10957-61
Authors Labahn J, Granzin J, Schluckebier G, Robinson DP, Jack WE, Schildkraut I, Saenger W
Title Three-dimensional structure of the adenine-specific DNA methyltransferase M.Taq I in complex with the cofactor S-adenosylmethionine.
Related PDB 1adm
Related UniProtKB P14385
[3]
Resource
Comments
Medline ID
PubMed ID 7607476
Journal Gene
Year 1995
Volume 157(1-2)
Pages 131-4
Authors Schluckebier G, Labahn J, Granzin J, Schildkraut I, Saenger W
Title A model for DNA binding and enzyme action derived from crystallographic studies of the TaqI N6-adenine-methyltransferase.
Related PDB
Related UniProtKB
[4]
Resource
Comments
Medline ID
PubMed ID 7897657
Journal J Mol Biol
Year 1995
Volume 247(1)
Pages 16-20
Authors Schluckebier G, O'Gara M, Saenger W, Cheng X
Title Universal catalytic domain structure of AdoMet-dependent methyltransferases.
Related PDB
Related UniProtKB
[5]
Resource
Comments
Medline ID
PubMed ID 8995524
Journal J Mol Biol
Year 1997
Volume 265(1)
Pages 56-67
Authors Schluckebier G, Kozak M, Bleimling N, Weinhold E, Saenger W
Title Differential binding of S-adenosylmethionine S-adenosylhomocysteine and Sinefungin to the adenine-specific DNA methyltransferase M.TaqI.
Related PDB 1aqi 1aqj 2adm
Related UniProtKB
[6]
Resource
Comments
Medline ID
PubMed ID 11175899
Journal Nat Struct Biol
Year 2001
Volume 8(2)
Pages 121-5
Authors Goedecke K, Pignot M, Goody RS, Scheidig AJ, Weinhold E
Title Structure of the N6-adenine DNA methyltransferase M.TaqI in complex with DNA and a cofactor analog.
Related PDB 1g38
Related UniProtKB

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.

Created Updated
2002-08-13 2009-02-26