KEGG ENZYME: 2.1.1.158

ENZYME: 2.1.1.158

Entry

EC 2.1.1.158                Enzyme

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)

R07917

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

ec00232

Caffeine metabolism

ec01100

Metabolic pathways

ec01110

Biosynthesis of secondary metabolites

Orthology

K12729

7-methylxanthosine synthase

Reference

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

2 [PMID:12860386]

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

FEBS Lett 547:56-60 (2003)
DOI:10.1016/S0014-5793(03)00670-7

Sequence

[ag:BAB39215]

Reference

3 [PMID:12746542]

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

Plant Physiol 132:372-80 (2003)
DOI:10.1104/pp.102.019679

Sequence

[ag:BAB39215]

Reference

4 [PMID:16333668]

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

Mol Genet Genomics 275:125-35 (2006)
DOI:10.1007/s00438-005-0070-z