A new buckwheat dihydroflavonol 4-reductase (DFR), with a unique substrate binding structure, has altered substrate...

Area of Science:

• Plant biochemistry
• Molecular biology
• Enzymology

Background:

• Dihydroflavonol 4-reductase (DFR) is crucial for anthocyanin and proanthocyanidin synthesis.
• DFR enzymes catalyze three main substrates with varying preferences.
• The molecular basis of DFR substrate specificity remains incompletely understood.

Purpose of the Study:

• To isolate and characterize DFR genes in buckwheat (Fagopyrum esculentum).
• To investigate the structural and functional differences between buckwheat DFRs.
• To elucidate the role of specific amino acid residues in DFR substrate specificity.

Main Methods:

• Degenerate primers and PCR were used to isolate cDNA clones.
• Sequence analysis and comparison of exon-intron structures were performed.
• Linkage analysis, 3D modeling, and enzyme activity assays were conducted.

Main Results:

• Two buckwheat DFR cDNA clones, FeDFR1a and FeDFR2, were isolated.
• FeDFR2 possesses distinct structural features, including unique amino acid substitutions in the substrate-specificity region.
• FeDFR2 showed lower activity with dihydrokaempferol and preferential expression in roots and seeds compared to FeDFR1a.

Conclusions:

• Two novel DFR genes were identified in buckwheat.
• FeDFR2 displays unique structural and functional characteristics compared to other plant DFRs.
• Amino acid residues in the substrate-binding pocket, including the third position, significantly influence DFR substrate preference.