Entry |
|
Name |
7-methylxanthosine synthase;
xanthosine methyltransferase;
XMT;
xanthosine:S-adenosyl-L-methionine methyltransferase;
CtCS1;
CmXRS1;
CaXMT1;
S-adenosyl-L-methionine:xanthosine 7-N-methyltransferase
|
Class |
Transferases;
Transferring one-carbon groups;
Methyltransferases
|
Sysname |
S-adenosyl-L-methionine:xanthosine N7-methyltransferase
|
Reaction(IUBMB) |
S-adenosyl-L-methionine + xanthosine = S-adenosyl-L-homocysteine + 7-methylxanthosine [RN: R07917]
|
Reaction(KEGG) |
|
Substrate |
S-adenosyl-L-methionine [CPD: C00019];
xanthosine [CPD: C01762]
|
Product |
S-adenosyl-L-homocysteine [CPD: C00021];
7-methylxanthosine [CPD: C16352]
|
Comment |
The enzyme is specific for xanthosine, as XMP and xanthine cannot act as substrates [2,4]. The enzyme does not have N1- or N3- methylation activity [2]. This is the first methylation step in the production of caffeine.
|
History |
EC 2.1.1.158 created 2007
|
Pathway |
ec01110 | Biosynthesis of secondary metabolites |
|
Orthology |
K12729 | 7-methylxanthosine synthase |
|
Reference |
1 |
Authors |
Negishi, O., Ozawa, T. and Imagawa, H. |
Title |
The role of xanthosine in the biosynthesis of caffeine in coffee plants. |
Journal |
Agric Biol Chem 49:2221-2222 (1985) |
Reference |
|
Authors |
Mizuno K, Kato M, Irino F, Yoneyama N, Fujimura T, Ashihara H |
Title |
The first committed step reaction of caffeine biosynthesis: 7-methylxanthosine synthase is closely homologous to caffeine synthases in coffee (Coffea arabica L.). |
Journal |
|
Sequence |
|
Reference |
|
Authors |
Uefuji H, Ogita S, Yamaguchi Y, Koizumi N, Sano H |
Title |
Molecular cloning and functional characterization of three distinct N-methyltransferases involved in the caffeine biosynthetic pathway in coffee plants. |
Journal |
|
Sequence |
|
Reference |
|
Authors |
Yoneyama N, Morimoto H, Ye CX, Ashihara H, Mizuno K, Kato M. |
Title |
Substrate specificity of N-methyltransferase involved in purine alkaloids synthesis is dependent upon one amino acid residue of the enzyme. |
Journal |
|
Other DBs |
ExPASy - ENZYME nomenclature database: | 2.1.1.158 |
|
LinkDB |
|