2EG5

The structure of xanthosine methyltransferase

2EG5 の概要

• エントリーDOI: 10.2210/pdb2eg5/pdb
• 関連するPDBエントリー: 2EFJ
• 分子名称: Xanthosine methyltransferase, S-ADENOSYL-L-HOMOCYSTEINE, 9-[(2R,3R,4S,5R)-3,4-DIHYDROXY-5-(HYDROXYMETHYL)OXOLAN-2-YL]-3H-PURINE-2,6-DIONE, ... (4 entities in total)
• 機能のキーワード: sam-dependant n-methyltransferase, xanthosine, sah, transferase
• 由来する生物種: Coffea canephora
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 170251.09

構造登録者

McCarthy, A.A.,McCarthy, J.G. (登録日: 2007-02-28, 公開日: 2007-05-01, 最終更新日: 2023-10-25)

主引用文献

McCarthy, A.A.,McCarthy, J.G.
The structure of two N-methyltransferases from the caffeine biosynthetic pathway
Plant Physiol., 144:879-889, 2007

PubMed Abstract: Caffeine (1,3,7-trimethylxanthine) is a secondary metabolite produced by certain plant species and an important component of coffee (Coffea arabica and Coffea canephora) and tea (Camellia sinensis). Here we describe the structures of two S-adenosyl-l-methionine-dependent N-methyltransferases that mediate caffeine biosynthesis in C. canephora 'robusta', xanthosine (XR) methyltransferase (XMT), and 1,7-dimethylxanthine methyltransferase (DXMT). Both were cocrystallized with the demethylated cofactor, S-adenosyl-L-cysteine, and substrate, either xanthosine or theobromine. Our structures reveal several elements that appear critical for substrate selectivity. Serine-316 in XMT appears central to the recognition of XR. Likewise, a change from glutamine-161 in XMT to histidine-160 in DXMT is likely to have catalytic consequences. A phenylalanine-266 to isoleucine-266 change in DXMT is also likely to be crucial for the discrimination between mono and dimethyl transferases in coffee. These key residues are probably functionally important and will guide future studies with implications for the biosynthesis of caffeine and its derivatives in plants.

PubMed: 17434991
DOI: 10.1104/pp.106.094854

実験手法

X-RAY DIFFRACTION (2.2 Å)