6LYH

Crystal structure of tea N9-methyltransferase CkTcS in complex with SAH and 1,3,7-trimethyluric acid

Summary for 6LYH

• Entry DOI: 10.2210/pdb6lyh/pdb
• Descriptor: N-methyltransferase CkTcS, S-ADENOSYL-L-HOMOCYSTEINE, 1,3,7-trimethyl-9H-purine-2,6,8-trione (3 entities in total)
• Functional Keywords: n-methyltransferase, cktcs, transferase
• Biological source: Camellia sinensis var. assamica
• Total number of polymer chains: 8
• Total formula weight: 331554.43

Authors

Wang, Y.,Zhang, Z.-M. (deposition date: 2020-02-14, release date: 2020-03-04, Last modification date: 2023-11-29)

Primary citation

Zhang, Y.H.,Li, Y.F.,Wang, Y.,Tan, L.,Cao, Z.Q.,Xie, C.,Xie, G.,Gong, H.B.,Sun, W.Y.,Ouyang, S.H.,Duan, W.J.,Lu, X.,Ding, K.,Kurihara, H.,Hu, D.,Zhang, Z.M.,Abe, I.,He, R.R.
Identification and characterization of N9-methyltransferase involved in converting caffeine into non-stimulatory theacrine in tea.
Nat Commun, 11:1473-1473, 2020

PubMed Abstract: Caffeine is a major component of xanthine alkaloids and commonly consumed in many popular beverages. Due to its occasional side effects, reduction of caffeine in a natural way is of great importance and economic significance. Recent studies reveal that caffeine can be converted into non-stimulatory theacrine in the rare tea plant Camellia assamica var. kucha (Kucha), which involves oxidation at the C8 and methylation at the N9 positions of caffeine. However, the underlying molecular mechanism remains unclear. Here, we identify the theacrine synthase CkTcS from Kucha, which possesses novel N9-methyltransferase activity using 1,3,7-trimethyluric acid but not caffeine as a substrate, confirming that C8 oxidation takes place prior to N9-methylation. The crystal structure of the CkTcS complex reveals the key residues that are required for the N9-methylation, providing insights into how caffeine N-methyltransferases in tea plants have evolved to catalyze regioselective N-methylation through fine tuning of their active sites. These results may guide the future development of decaffeinated drinks.

PubMed: 32193380
DOI: 10.1038/s41467-020-15324-7

Experimental method

X-RAY DIFFRACTION (3.15000316024 Å)