何首乌中一种Ⅲ型PKS基因的克隆及生物信息学分析

Ⅲ型聚酮合酶即查耳酮合酶超家族，能催化生成一系列结构各异、具有不同生理活性、含有查耳酮合酶基本骨架的植物次生代谢产物。根据不同植物Ⅲ型PKSs基因的保守序列,设计简并引物,采用RT - PCR和RACE技术,首次从传统中药材何首乌(Polygonum multiflorum Thunb.)中克隆到一种Ⅲ型PKS基因，其cDNA全长1228bp, 编码379个氨基酸，命名为FmPKS (GenBank登录号: GQ411431)。该基因含有三个内含子, 与迄今报道的绝大部分Ⅲ型PKS含有一个内含子不同，而与最近报道的虎杖中克隆的PcPKS2基因相同。通过生物信息学方法对其编码蛋白的序列进行同源性分析，构建了系统进化树，并对其等电点、疏水性及二级结构、跨膜区域等理化性质进行了初步预测,为进一步研究其功能奠定了基础。

Gene cloning and Bioinformatics Analysis of a kind of type Ⅲ polyketide synthase in Polygonum multiflorum Thunb.

Type Ⅲ Polyketide synthases (PKSs) from plant produce an array of plant secondary metabolite including chalcone scaffolds but with different biological activities and pharmacological properties. Based on the conservative type Ⅲ polyketide synthase（PKS）gene sequence in plants, the degenerate primers were designed, and a kind of type Ⅲ PKS gene in Polygonum multiflorum Thunb. named FmPKS (GenBank accession number: GQ411431) was cloned for the first time by RT-PCR and RACE. It was found that the coding sequence of the gene consisted of the 1228 bp nucleotides which encoded 378 amino acids. Sequencing results showed that the ORF of FmPKS was interrupted by three introns, which was different from all type Ⅲ PKS genes studied so far contained only one intron at a conserved site in flowering plants, but the same as the recent cloned gene PcPKS2 from Polygonum cuspidatum Sieb. Based on homologous sequence analysis the the Phylogenetic tree was constructed, and the bioinformatics methods was used to predict the isoelectric point, hydrophobicity, and the secondary structure, which will lay the foundation for further studying its gene function .