title: Flavone synthases from Lonicera japonica and L. macranthoides reveal differential flavone accumulation.
abstract: Flavones are important secondary metabolites found in many plants. In Lonicera species, flavones contribute both physiological and pharmaceutical properties. However, flavone synthase (FNS), the key enzyme responsible for flavone biosynthesis, has not yet been characterized in Lonicera species. In this study, FNSII genes were identified from Lonicera japonica Thunb. and L. macranthoides Hand.-Mazz. In the presence of NADPH, the recombinant cytochrome P450 proteins encoded by LjFNSII-1.1, LjFNSII-2.1, and LmFNSII-1.1 converted eriodictyol, naringenin, and liquiritigenin to the corresponding flavones directly. The different catalytic properties between LjFNSII-2.1 and LjFNSII-1.1 were caused by a single amino acid substitution at position 242 (glutamic acid to lysine). A methionine at position 206 and a leucine at position 381 contributed considerably to the high catalytic activity of LjFNSII-1.1. In addition, LjFNSII-1.1&2.1 and LmFNSII-1.1 also biosynthesize flavones that were further modified by O-glycosylation in transgenic tobacco. The expression levels of the FNSII genes were consistent with flavone accumulation patterns in flower buds. Our findings suggested that the weak catalytic activity of LmFNSII-1.1 and the relatively low expression of LmFNSII-1.1 in flowers might be responsible for the low levels of flavone accumulation in flower buds of L. macranthoides.
authors.affiliation: Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Wu
authors.affiliation: University of Chinese Academy of Sciences, Beijing 100049, China.|Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Xiao-Chen
authors.initials: XC
authors.lastname: Wang
authors.affiliation: Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Du
authors.affiliation: Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Qing-Yan
authors.initials: QY
authors.lastname: Shu
authors.affiliation: Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Shang
authors.initials: S
authors.lastname: Su
authors.affiliation: Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Li-Jin
authors.initials: LJ
authors.lastname: Wang
authors.affiliation: Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Li
authors.affiliation: Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Liang-Sheng
authors.initials: LS
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D053898:Biosynthetic Pathways; D002384:Catalysis; D004789:Enzyme Activation; D047309:Flavones / Q000378:metabolism*; D015870:Gene Expression; D031239:Lonicera / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D011487:Protein Conformation; D021381:Protein Transport; D011994:Recombinant Proteins
chemical_list: D047309:Flavones; D011994:Recombinant Proteins; D006899:Mixed Function Oxygenases