6lyi

From Proteopedia

Crystal structure of a N-methyltransferase CkTbS from Camellia assamica var. kucha

Structural highlights

6lyi is a 2 chain structure with sequence from Camellia sinensis var. assamica. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.49Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

TCS1_CAMSI Involved in the biosynthesis of caffeine (PubMed:10984041, PubMed:16333668, PubMed:26773541, PubMed:30303011, PubMed:25133732). Catalyzes the conversion of 7-methylxanthine (7mX) to theobromine and of theobromine to caffeine (PubMed:10984041, PubMed:16333668, PubMed:26773541, PubMed:30303011, PubMed:25133732). Has 3-N- and 1-N-methylation activity (PubMed:10984041, PubMed:16333668).^[1] ^[2] ^[3] ^[4] ^[5]

Publication Abstract from PubMed

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.

Identification and characterization of N9-methyltransferase involved in converting caffeine into non-stimulatory theacrine in tea.,Zhang YH, Li YF, Wang Y, Tan L, Cao ZQ, Xie C, Xie G, Gong HB, Sun WY, Ouyang SH, Duan WJ, Lu X, Ding K, Kurihara H, Hu D, Zhang ZM, Abe I, He RR Nat Commun. 2020 Mar 19;11(1):1473. doi: 10.1038/s41467-020-15324-7. PMID:32193380^[6]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Kato M, Mizuno K, Crozier A, Fujimura T, Ashihara H. Caffeine synthase gene from tea leaves. Nature. 2000 Aug 31;406(6799):956-7. PMID:10984041 doi:10.1038/35023072
↑ Yoneyama N, Morimoto H, Ye CX, Ashihara H, Mizuno K, Kato M. Substrate specificity of N-methyltransferase involved in purine alkaloids synthesis is dependent upon one amino acid residue of the enzyme. Mol Genet Genomics. 2006 Feb;275(2):125-35. PMID:16333668 doi:10.1007/s00438-005-0070-z
↑ Jin L, Bhuiya MW, Li M, Liu X, Han J, Deng W, Wang M, Yu O, Zhang Z. Metabolic engineering of Saccharomyces cerevisiae for caffeine and theobromine production. PLoS One. 2014 Aug 18;9(8):e105368. PMID:25133732 doi:10.1371/journal.pone.0105368
↑ Jin JQ, Yao MZ, Ma CL, Ma JQ, Chen L. Natural allelic variations of TCS1 play a crucial role in caffeine biosynthesis of tea plant and its related species. Plant Physiol Biochem. 2016 Mar;100:18-26. PMID:26773541 doi:10.1016/j.plaphy.2015.12.020
↑ Jin JQ, Chai YF, Liu YF, Zhang J, Yao MZ, Chen L. Hongyacha, a Naturally Caffeine-Free Tea Plant from Fujian, China. J Agric Food Chem. 2018 Oct 31;66(43):11311-11319. PMID:30303011 doi:10.1021/acs.jafc.8b03433
↑ Zhang YH, Li YF, Wang Y, Tan L, Cao ZQ, Xie C, Xie G, Gong HB, Sun WY, Ouyang SH, Duan WJ, Lu X, Ding K, Kurihara H, Hu D, Zhang ZM, Abe I, He RR. Identification and characterization of N9-methyltransferase involved in converting caffeine into non-stimulatory theacrine in tea. Nat Commun. 2020 Mar 19;11(1):1473. doi: 10.1038/s41467-020-15324-7. PMID:32193380 doi:http://dx.doi.org/10.1038/s41467-020-15324-7