Kodan Atsushi, Kuroda Hiroyuki, Sakai Fukumi
Wood Research Institute, Kyoto University, Uji, Kyoto 611-0011, Japan.
Proc Natl Acad Sci U S A. 2002 Mar 5;99(5):3335-9. doi: 10.1073/pnas.042698899.
Stilbene synthase (STS) and chalcone synthase (CHS) are plant-specific polyketide synthases that play key roles in the stilbenoid and flavonoid biosyntheses, respectively. We have recently isolated from Pinus densiflora three STS cDNAs (PDSTS1, PDSTS2, and PDSTS3) and one CHS cDNA (PDCHSX). We then heterologously expressed these cDNAs in Escherichia coli and characterized their properties. An unusual STS isozyme, PDSTS3, lacks the common C-terminal extension of STS because of a frame-shift mutation and shows the highest pinosylvin-forming activity among the STSs tested. Pinosylvin was shown to be a potent inhibitor of PDCHSX (K(i) = 6 microM) as well as PDSTS2 (K(i) = 13 microM), which presumably maintains the balance between the stilbenoid and flavonoid biosyntheses. PDSTS3 was insensitive to product inhibition. We identified PDSTS3 in the pine seedlings as well as full-length STS. The data provide evidence that PDSTS3 is involved in the potential regulation of the stilbenoid and flavonoid biosynthetic pathways in pine trees.
芪合酶（STS）和查尔酮合酶（CHS）是植物特有的聚酮合酶，分别在芪类化合物和类黄酮生物合成中起关键作用。我们最近从赤松中分离出三个STS cDNA（PDSTS1、PDSTS2和PDSTS3）和一个CHS cDNA（PDCHSX）。然后我们在大肠杆菌中对这些cDNA进行了异源表达并表征了它们的特性。一种不寻常的STS同工酶PDSTS3，由于移码突变而缺乏STS常见的C末端延伸，并且在所测试的STS中显示出最高的生成松脂醇的活性。松脂醇被证明是PDCHSX（K(i)=6 microM）以及PDSTS2（K(i)=13 microM）的有效抑制剂，这可能维持了芪类化合物和类黄酮生物合成之间的平衡。PDSTS3对产物抑制不敏感。我们在松树幼苗以及全长STS中鉴定出了PDSTS3。这些数据提供了证据，表明PDSTS3参与了松树中芪类化合物和类黄酮生物合成途径的潜在调控。
