Identification of a Polygonum cuspidatum three-intron gene encoding a type III polyketide synthase producing both naringenin and p-hydroxybenzalacetone
Identification of a Polygonum cuspidatum three-intron gene encoding a type III polyketide synthase producing both naringenin and p-hydroxybenzalacetone
复制标题
DOI：
10.1007/s00425-009-0899-1
复制
发表时间：
2009-04-01
期刊：
影响因子：
4.3
通讯作者：
Ye, He-Chun
中科院分区：
文献类型：
--
作者：
Ma, Lan-Qing;Guo, Yan-Wu;Ye, He-Chun
苄叉丙酮合酶（BAS）是植物特异性III型PKS超家族的成员，其催化4-香豆酰-CoA与丙二酰-CoA的一步脱羧缩合以产生对羟基苄叉丙酮。在我们最近的工作中（Ma等，Planta 229（3）：457-469，2008），从虎杖（Polygonum cuspidatum Sieb.）et Zucc.系统发育和功能分析表明，该重组PcPKS 2是一个BAS。本研究从虎杖中克隆了另一个含三个内含子的Ⅲ型PKS基因（PcPKS 1）及其相应的cDNA。序列分析和系统发育分析表明PcPKS 1是一种查尔酮合酶（CHS）。然而，功能和酶的分析表明，重组PcPKS 1是一个双功能酶，CHS和BAS活性。DNA凝胶印迹分析表明，虎杖基因组中存在2 ~ 4个CHS拷贝。RNA凝胶印迹分析表明，PcPKS 1是高度表达的根茎和幼叶，但不是在植物的根。PcPKS 1基因在叶片中的转录是可诱导的病原菌感染和创伤。BAS被认为在各种苯基丁烷类化合物中发现的C6-C4部分的构建中起关键作用，但迄今为止尚未从虎杖中分离出苯基丁烷类化合物。然而，由于PcPKS 1和PcPKS 2（Ma等人，Planta 229（3）：457-469，2008）已经在虎杖中被鉴定，因此可能的是，这样的化合物也在该植物中产生，尽管浓度低。
Benzalacetone synthase (BAS) is a member of the plant-specific type III PKS superfamily that catalyzes a one-step decarboxylative condensation of 4-coumaroyl-CoA with malonyl-CoA to produce p-hydroxybenzalacetone. In our recent work (Ma et al. in Planta 229(3):457-469, 2008), a three-intron type III PKS gene (PcPKS2) was isolated from Polygonum cuspidatum Sieb. et Zucc. Phylogenetic and functional analyses revealed this recombinant PcPKS2 to be a BAS. In this study, another three-intron type III PKS gene (PcPKS1) and its corresponding cDNA were isolated from P. cuspidatum. Sequence and phylogenetic analyses demonstrated that PcPKS1 is a chalcone sythase (CHS). However, functional and enzymatic analyses showed that recombinant PcPKS1 is a bifunctional enzyme with both, CHS and BAS activity. DNA gel blot analysis indicated that there are two to four CHS copies in the P. cuspidatum genome. RNA gel blot analysis revealed that PcPKS1 is highly expressed in the rhizomes and in young leaves, but not in the roots of the plant. PcPKS1 transcripts in leaves were inducible by pathogen infection and wounding. BAS is thought to play a crucial role in the construction of the C6-C4 moiety found in a variety of phenylbutanoids, yet so far phenylbutanoids have not been isolated from P. cuspidatum. However, since PcPKS1 and PcPKS2 (Ma et al. in Planta 229(3): 457-469, 2008) have been identified in P. cuspidatum, it is possible that such compounds are also produced in that plant, albeit in low concentrations.