PDBsum entry 6lyh

Transferase

PDB id: 6lyh

Contents

Protein chains

(+ 2 more) 350 a.a.

Ligands

SAH ×8

EXU ×8

PDB id:

6lyh

Name:

Transferase

Title:

Crystal structure of tea n9-methyltransferase cktcs in complex with sah and 1,3,7-trimethyluric acid

Structure:

N-methyltransferase cktcs. Chain: b, a, c, d, e, f, g, h. Engineered: yes

Source:

Camellia sinensis var. Assamica. Organism_taxid: 261999. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

3.15Å R-factor: 0.264 R-free: 0.298

Authors:

Y.Wang,Z.-M.Zhang

Key ref:

Y.H.Zhang et al. (2020). Identification and characterization of N9-methyltransferase involved in converting caffeine into non-stimulatory theacrine in tea. Nat Commun, 11, 1473. PubMed id: 32193380 DOI: 10.1038/s41467-020-15324-7

Date:

14-Feb-20 Release date: 04-Mar-20

Protein chains

Q9FZN8  (TCS1_CAMSI) -  3,7-dimethylxanthine N-methyltransferase TCS1 from Camellia sinensis

Seq: 369 a.a.

Struc: 350 a.a.*

* PDB and UniProt seqs differ at 27 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.2.1.1.160 - caffeine synthase.
• Reaction:
  1. theobromine + S-adenosyl-L-methionine = caffeine + S-adenosyl-L- homocysteine + H⁺
  2. 1,7-dimethylxanthine + S-adenosyl-L-methionine = caffeine + S-adenosyl-L-homocysteine + H⁺
  3. 7-methylxanthine + S-adenosyl-L-methionine = theobromine + S-adenosyl-L-homocysteine + H⁺

theobromine + S-adenosyl-L-methionine = caffeine (Bound ligand (Het Group name = EXU) matches with 93.33% similarity) + S-adenosyl-L- homocysteine + H(+) (Bound ligand (Het Group name = SAH) corresponds exactly)

1,7-dimethylxanthine + S-adenosyl-L-methionine = caffeine (Bound ligand (Het Group name = EXU) matches with 93.33% similarity) + S-adenosyl-L-homocysteine + H(+) (Bound ligand (Het Group name = SAH) corresponds exactly)

7-methylxanthine + S-adenosyl-L-methionine = theobromine + S-adenosyl-L-homocysteine (Bound ligand (Het Group name = SAH) corresponds exactly) + H(+) (Bound ligand (Het Group name = EXU) matches with 86.67% similarity)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1038/s41467-020-15324-7

Nat Commun 11:1473 (2020)

PubMed id: 32193380

Identification and characterization of N9-methyltransferase involved in converting caffeine into non-stimulatory theacrine in tea.

Y.H.Zhang, Y.F.Li, Y.Wang, L.Tan, Z.Q.Cao, C.Xie, G.Xie, H.B.Gong, W.Y.Sun, S.H.Ouyang, W.J.Duan, X.Lu, K.Ding, H.Kurihara, D.Hu, Z.M.Zhang, I.Abe, R.R.He.

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.