title: Functional expression of geraniol 10-hydroxylase reveals its dual function in the biosynthesis of terpenoid and phenylpropanoid.
abstract: Geraniol 10-hydroxylase (G10H), a cytochrome P450 monooxygenase, has been reported to be involved in the biosynthesis of terpenoid indole alkaloids. The gene for Catharanthus roseus G10H (CrG10H) was cloned and heterologously expressed in baculovirus-infected insect cells. A number of substrates were subjected to assay the enzyme activity of CrG10H. As reported in a previous study, CrG10H hydroxylated the monoterpenoid geraniol at the C-10 position to generate 10-hydroxygeraniol. Interestingly, CrG10H also catalyzed 3'-hydroxylation of naringenin to produce eriodictyol. Coexpression of an Arabidopsis NADPH P450 reductase substantially increased the ability of CrG10H to hydroxylate naringenin. The catalytic activity of CrG10H was approximately 10 times more efficient with geraniol than with naringenin, judged by the k(cat)/K(m) values. Thus, G10H also plays an important role in the biosynthetic pathway of flavonoids, in addition to its previously described role in the metabolism of terpenoids.
authors.affiliation: Department of Horticulture, National Taiwan University, Taipei, Taiwan, Republic of China.
authors.forename: Pin-Hui
authors.initials: PH
authors.lastname: Sung
authors.forename: Fong-Chin
authors.initials: FC
authors.lastname: Huang
authors.forename: Yi-Yin
authors.initials: YY
authors.lastname: Do
authors.forename: Pung-Ling
authors.initials: PL
authors.lastname: Huang
mesh_terms: D053898:Biosynthetic Pathways; D030008:Catharanthus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D007700:Kinetics; D010666:Phenylpropionates / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013729:Terpenes / Q000378:metabolism*
chemical_list: D010666:Phenylpropionates; D010940:Plant Proteins; D013729:Terpenes; D003577:Cytochrome P-450 Enzyme System; C081675:geraniol 10-hydroxylase