View source for 6lyi


==Crystal structure of a N-methyltransferase CkTbS from Camellia assamica var. kucha==
<StructureSection load='6lyi' size='340' side='right'caption='[[6lyi]], [[Resolution|resolution]] 2.49&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6lyi]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Camellia_sinensis_var._assamica Camellia sinensis var. assamica]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6LYI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6LYI FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.49&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6lyi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6lyi OCA], [https://pdbe.org/6lyi PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6lyi RCSB], [https://www.ebi.ac.uk/pdbsum/6lyi PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6lyi ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/TCS1_CAMSI 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).<ref>PMID:10984041</ref> <ref>PMID:16333668</ref> <ref>PMID:25133732</ref> <ref>PMID:26773541</ref> <ref>PMID:30303011</ref> 
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== 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<ref>PMID:32193380</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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</StructureSection>
[[Category: Camellia sinensis var. assamica]]
[[Category: Large Structures]]
[[Category: Wang Y]]
[[Category: Zhang ZM]]