title: Alteration of a single amino acid changes the substrate specificity of dihydroflavonol 4-reductase.
abstract: Many plant species exhibit a reduced range of flower colors due to the lack of an essential gene or to the substrate specificity of a biosynthetic enzyme. Petunia does not produce orange flowers because dihydroflavonol 4-reductase (DFR) from this species, an enzyme involved in anthocyanin biosynthesis, inefficiently reduces dihydrokaempferol, the precursor to orange pelargonidin-type anthocyanins. The substrate specificity of DFR, however, has not been investigated at the molecular level. By analyzing chimeric DFRs of Petunia and Gerbera, we identified a region that determines the substrate specificity of DFR. Furthermore, by changing a single amino acid in this presumed substrate-binding region, we developed a DFR enzyme that preferentially reduces dihydrokaempferol. Our results imply that the substrate specificity of DFR can be altered by minor changes in DFR.
authors.affiliation: Kumho Life and Environmental Science Laboratory, 1 Oryong-dong, Puk-gu, Kwangju 500-712 Korea.
authors.forename: E T
authors.initials: ET
authors.lastname: Johnson
authors.forename: S
authors.initials: S
authors.lastname: Ryu
authors.forename: H
authors.initials: H
authors.lastname: Yi
authors.forename: B
authors.initials: B
authors.lastname: Shin
authors.forename: H
authors.initials: H
authors.lastname: Cheong
authors.forename: G
authors.initials: G
authors.lastname: Choi
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D017931:DNA Primers; D019684:Magnoliopsida / Q000201:enzymology; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D017931:DNA Primers; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase