Alteration of a single amino acid changes the substrate specificity of dihydroflavonol 4-reductase.
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.
Johnson
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ET
Kumho Life and Environmental Science Laboratory, 1 Oryong-dong, Puk-gu, Kwangju 500-712 Korea.
Ryu
S
S
Yi
H
H
Shin
B
B
Cheong
H
H
Choi
G
G
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
D017931:DNA Primers; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase