Two-step epoxidation of hyoscyamine to scopolamine is catalyzed by bifunctional hyoscyamine 6 beta-hydroxylase.
In several solanaceous plants, hyoscyamine is first hydroxylated at the 6 beta-position, and then epoxidized to scopolamine. We expressed hyoscyamine 6 beta-hydroxylase (H6H) in Escherichia coli as a fusion protein with maltose-binding protein. The crude cell extract from the bacterium that expressed the soluble fusion protein showed a strong hydroxylase activity and a weak epoxidase activity. When 100 microM of hyoscyamine was fed to the recombinant bacterium, the alkaloid was first converted to 6 beta-hydroxy hyoscyamine, and then to scopolamine, which was almost the only alkaloid found in the culture after one week. Therefore, H6H catalyzes two consecutive reactions that oxidize hyoscyamine to scopolamine.
Hashimoto
T
T
Department of Agricultural Chemistry, Faculty of Agriculture, Kyoto University, Japan.
Matsuda
J
J
Yamada
Y
Y
D018528:ATP-Binding Cassette Transporters; D001285:Atropine / Q000378:metabolism*; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics; D002384:Catalysis; D004247:DNA / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins; D015870:Gene Expression; D058619:Maltose-Binding Proteins; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D010088:Oxidoreductases / Q000378:metabolism; D010944:Plants / Q000201:enzymology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012601:Scopolamine / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D011993:Recombinant Fusion Proteins; C461599:maltose transport system, E coli; D001285:Atropine; D004247:DNA; D012601:Scopolamine; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; C023111:epoxidase; C052273:hyoscyamine (6S)-dioxygenase