Key Laboratory of Chemical Biology of Natural Products, Ministry of Education School of Pharmaceutical Sciences, Shandong University, Jinan, 250012, China.
Plant Cell Rep. 2015 Feb;34(2):233-45. doi: 10.1007/s00299-014-1702-8. Epub 2014 Nov 18.
A chalcone synthase gene ( PaCHS ) was isolated and functionally characterized from liverwort. The ectopic expression of PaCHS in Marchantia paleacea callus raised the flavonoids content. Chalcone synthase (CHS; EC 2.3.1.74) is pivotal for the biosynthesis of flavonoid and anthocyanin pigments in plants. It produces naringenin chalcone by condensing one p-coumaroyl- and three malonyl-coenzyme A thioesters through a polyketide intermediate that is cyclized by intramolecular Claisen condensation. Although CHSs of higher plants have been extensively studied, enzyme properties of the CHSs in liverworts have been scarcely characterized. In this study, we report the cloning and characterization of CHS (designated as PaCHS) from the liverwort Plagiochasma appendiculatum. The gene product was 60-70 % identical with chalcone synthases from other species, and contained the characteristic conserved Cys-His-Asn catalytic triad. The recombinant PaCHS was able to catalyze p-coumaroyl-CoA and malonyl-CoA to generate naringenin in vitro. Heterologously expressed PaCHS protein showed similar kinetic properties to those of higher plant CHS. The ectopic expression of PaCHS in Marchantia paleacea callus raised the content of the total flavonoids. These results suggested that PaCHS played a key role in the flavonoids biosynthesis in liverworts. Furthermore, when the thallus of P. appendiculatum was treated with abiotic stress inducers methyl jasmonate, salicylic acid and abscisic acid, PaCHS expression was enhanced. This is the first time that a CHS in liverworts has been functionally characterized.
从地钱中分离并鉴定出一种查尔酮合酶基因（PaCHS）。在叶苔愈伤组织中异位表达 PaCHS 提高了类黄酮含量。查尔酮合酶（CHS；EC 2.3.1.74）是植物类黄酮和花青素生物合成的关键酶。它通过缩合一个对香豆酰-CoA 和三个丙二酰-CoA 硫酯，形成一个聚酮中间体，然后通过分子内克莱森缩合环化，生成柚皮素查尔酮。虽然高等植物的 CHS 已经得到了广泛的研究，但地钱中的 CHS 酶性质却很少被描述。在这项研究中，我们从地钱 Plagiochasma appendiculatum 中克隆并鉴定了 CHS（命名为 PaCHS）。该基因产物与其他物种的查尔酮合酶有 60-70%的同一性，并且包含特征性的保守半胱氨酸-组氨酸-天冬酰胺催化三联体。重组 PaCHS 能够在体外催化对香豆酰-CoA 和丙二酰-CoA 生成柚皮素。异源表达的 PaCHS 蛋白表现出与高等植物 CHS 相似的动力学特性。在叶苔愈伤组织中异位表达 PaCHS 提高了总类黄酮的含量。这些结果表明 PaCHS 在植物类黄酮生物合成中起着关键作用。此外，当地钱的叶状体受到生物胁迫诱导剂茉莉酸甲酯、水杨酸和脱落酸处理时，PaCHS 的表达增强。这是首次对地钱中的 CHS 进行功能鉴定。
