Johnson E T, Ryu S, Yi H, Shin B, Cheong H, Choi G
Kumho Life and Environmental Science Laboratory, 1 Oryong-dong, Puk-gu, Kwangju 500-712 Korea.
Plant J. 2001 Feb;25(3):325-33. doi: 10.1046/j.1365-313x.2001.00962.x.
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.
由于缺乏必需基因或生物合成酶的底物特异性，许多植物物种呈现出有限的花色范围。矮牵牛不产生橙色花朵，因为该物种的二氢黄酮醇4-还原酶（DFR），一种参与花青素生物合成的酶，不能有效地还原二氢山奈酚，即橙色天竺葵素型花青素的前体。然而，DFR的底物特异性尚未在分子水平上进行研究。通过分析矮牵牛和非洲菊的嵌合DFR，我们确定了一个决定DFR底物特异性的区域。此外，通过改变这个假定的底物结合区域中的一个氨基酸，我们开发出了一种优先还原二氢山奈酚的DFR酶。我们的结果表明，DFR的底物特异性可以通过DFR的微小变化而改变。
