摘要： 为了丰富芍药CHI基因研究的基础数据,首先利用RACE技术对芍药CHI基因的CDS区进行克隆,并通过EMBOSS软件分析序列的密码子偏好性,其次利用生物信息学软件和在线数据库对芍药CHI进行蛋白结构与功能预测。结果表明,克隆获得芍药CHI基因cDNA序列长度为898 bp(GenBank序列号:JN119872),芍药CHI基因偏好使用以A/U结尾的密码子,28种偏好密码子(RSCU > 1),其中偏好性较强的有UUG、UGU、CAU、AGA、AGG、CGG(RSCU≥2),在密码子的使用频率上,芍药CHI基因与酵母、大肠杆菌等模式生物基因组的差异均大于拟南芥基因组。芍药CHI为非跨膜亲水的稳定蛋白,无信号肽,属于非分泌蛋白;主要分布在细胞质(45.0%)和微体(42.5%)中;无糖基化位点,14个磷酸化位点,其中第20位氨基酸处存在一个典型的磷酸激酶PKC,含有1个异构酶Chalcone保守结构域;二级结构包括α螺旋(39%)、延伸链(20%)、β-转角结构(13%)和无规则卷曲(27%);三级结构呈β-三明治折叠形成的倒置花束。发现了一个异构酶催化活性区域和一个重要的特异性蛋白质激酶PKC位点,为今后深入研究CHI基因功能提供有利的基础资料,此外,拟南芥真核表达更适合作为芍药CHI基因的外源表达系统。

关键词: 芍药, CHI基因, 密码子偏好性, 蛋白结构与功能

Abstract: In order to enrich basic data in Paeonia lactiflora CHI gene, the CDS region of Paeonia lactiflora CHI gene was cloned by RACE technology, further codon usage was analyzed by EMBOSS software, then the structure and function of CHI protein was predicted by bioinformatics software and online databases.Results indicated that, the 898 bp full-length cDNA of CHI of Paeonia lactiflora (GenBank No.:JN119872)was obtained.Paeonia lactiflora CHI gene has certain preference of codon usage with the terminal base A or U.There were twenty-eight biased codons(RSCU > 1), whose biased strongly codons were UUG, UGU, CAU, AGA, AGG and CGG(RSCU≥2).In codon usage frequency, the differences between CHI gene and Saccharomyces, E.coli genomes were more than Arabidopsis genome.CHI was non-transmembrane and hydrophilic protein with no signal peptide, which located mostly in cytoplasm(45.0%) and microbody(42.5%) by the result of subcellular level prediction and does not belong to the secretory protein.CHI protein had no glycosylation sites and fourteen phosphorylation sites, including a PKC kinase located in 20th amino acid.Additionally, it had one conservative domain named chalcone.The secondary structure of CHI protein contained 39% α-helices, 20% extended strand, 13% β-turn and 27% random coil.Tertiary structure presented an inversion bouquet by beta sandwich folding.In this study, we found one conservative domain responsible for catalytic activity of isomerase and an specific protein kinases PKC site, which will provide advantageous basic data for further studying CHI gene function.Moreover, the eukaryotic Saccharomyces expression systems may be more suitable for the expression of CHI gene.

Key words: Paeonia lactiflora, CHI gene, Codon usage bias, Protein structure and function

中图分类号: 

• Q78

• S682.03