{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T22:59:37Z","timestamp":1791327577364,"version":"4.3.1"},"reference-count":26,"publisher":"Oxford University Press (OUP)","issue":"1","license":[{"start":{"date-parts":[[2003,5,1]],"date-time":"2003-05-01T00:00:00Z","timestamp":1051747200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/journals\/pages\/open_access\/funder_policies\/chorus\/standard_publication_model"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2003,5,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:p>Caffeine is synthesized from xanthosine throughN-methylation and ribose removal steps. In the present study, three types of cDNAs encodingN-methyltransferases were isolated from immature fruits of coffee (Coffea arabica) plants, and designated asCaXMT1, CaMXMT2, andCaDXMT1, respectively. The bacterially expressed encoded proteins were characterized for their catalytic properties. CaXMT1 catalyzed formation of 7-methylxanthosine from xanthosine with aK \u00a0m value of 78 \u03bcm, CaMXMT2 catalyzed formation of 3,7-dimethylxanthine (theobromine) from 7-methylxanthine with a K \u00a0m of 251 \u03bcm, and CaDXMT1 catalyzed formation of 1,3,7-trimethylxanthine (caffeine) from 3,7-dimethylxanthine with aK \u00a0m of 1,222 \u03bcm. The crude extract of Escherichia coli was found to catalyze removal of the ribose moiety from 7-methylxanthosine, leading to the production of 7-methylxanthine. As a consequence, when all three recombinant proteins and E. coli extract were combined, xanthosine was successfully converted into caffeine in vitro. Transcripts for CaDXMT1 were predominantly found to accumulate in immature fruits, whereas those for CaXMT1and CaMXMT2 were more broadly detected in sites encompassing the leaves, floral buds, and immature fruits. These results suggest that the presently identified threeN-methyltransferases participate in caffeine biosynthesis in coffee plants and substantiate the proposed caffeine biosynthetic pathway: xanthosine \u2192 7-methylxanthosine \u2192 7-methylxanthine \u2192 theobromine \u2192 caffeine.<\/jats:p>","DOI":"10.1104\/pp.102.019679","type":"journal-article","created":{"date-parts":[[2003,5,13]],"date-time":"2003-05-13T20:28:46Z","timestamp":1052857726000},"page":"372-380","source":"Crossref","is-referenced-by-count":136,"title":["Molecular Cloning and Functional Characterization of Three Distinct <i>N<\/i>-Methyltransferases Involved in the Caffeine Biosynthetic Pathway in Coffee Plants"],"prefix":"10.1093","volume":"132","author":[{"given":"Hirotaka","family":"Uefuji","sequence":"first","affiliation":[{"name":"Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Nara 630\u20130192, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shinjiro","family":"Ogita","sequence":"additional","affiliation":[{"name":"Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Nara 630\u20130192, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yube","family":"Yamaguchi","sequence":"additional","affiliation":[{"name":"Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Nara 630\u20130192, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nozomu","family":"Koizumi","sequence":"additional","affiliation":[{"name":"Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Nara 630\u20130192, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hiroshi","family":"Sano","sequence":"additional","affiliation":[{"name":"Research and Education Center for Genetic Information, Nara 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