彩色马铃薯类黄酮-3-O-葡萄糖基转移酶基因(3GT)的生物信息学和表达分析

Bioinformatical and Expression Analysis of UDP-glucose: Flavonoid-3-O-Glucosyltransferase Gene from Pigmented Potato

类黄酮-3-O-葡萄糖基转移酶（3GT）能催化无色的花色素生成有色的花色苷。本研究采用RT-PCR法从彩色马铃薯中克隆了3GT基因,并对其进行了生物信息学分析和组织表达模式分析。结果显示,3GT基因编码448个氨基酸残基,具有信号肽但无跨膜结构域,还有一定的亲水性,定位于细胞质。同源比对表明3GT与茄子等茄科植物同属一簇,亲缘关系最近,与玉米等单子叶植物亲缘关系较远。3GT蛋白主要的二级结构元件为α-螺旋和无规则卷曲,且只有一个功能结构域,即氨基酸序列中的93~407区段,它与UDP-glucoronosyl、UDP-glucosyl transferase的功能结构域相匹配,因此,3GT属于UDPGT型糖基转移酶超家族的一员。组织特异性表达结果表明：3GT相对表达量和花色苷含量均是块茎高于叶片,它们的变化趋势基本一致,花色苷含量较高的器官,其3GT的相对表达量也较高,说明花色苷的积累与3GT的表达正相关。本研究可为花色苷积累的生化及分子机制研究奠定基础,并为进一步研究该基因在花色苷合成途径中的调控功能提供理论依据。

Flavonoid-3-O-glucosyltransferase gene（3GT） can add sugar residues to achromic anthocyanidin and synthesize chromatic anthocyanin. In this study, the complete c DNA of 3GTs were isolated from pigmented potato（Solanum tuberosum L.） by Reverse Transcription-Polymerase Chain Reaction（RT-PCR）. The sequence information and expression pattern of 3GTs were analyzed by tools of bioinformatics and Real time Quantitative PCR（q RT-PCR）. The 3GT encoded 448 amino acid residues and had signal peptide but without transmembrane structure region. The 3GT may be a kind of hydrophilic protein which probably located in cytoplasm. Through multiple sequences alignment of 3GTs, a homology tree was constructed. The 3GTs of pigmented potato were clustered together with Solanaceae plants and this result indicated that they had the closest phylogenetic relationship. The3 GTs of pigmented potato had the farthest phylogenetic relationship with monocotyledon like maize. α-helix and random coil were primary secondary structural components of 3GT. The 3GT protein only had one functional domain which was 93~407 segment in the amino acid sequence. The functional domain of 3GT matched UDP-glucoronosyl and UDP-glucosyl transferase＇s, therefore, 3GT protein belong to UDP-glucosyl transferase superfamily. The mRNA expression analysis by real-time quantitative PCR demonstrated that the accumulation of3 GT transcripts in tuber were much more than that in leaf. It indicated that the expression of 3GT gene was followed by anthocyanin accumulation. The activity of 3GT was dramatically and positively correlated with the content of anthocyanin. This study could lay a foundation for the study of biochemical and molecular mechanism of anthocyanin accumulation, and provide a theoretical basis for further research on the gene regulatory function in anthocyanin synthesis pathway.