巴西蕉多酚氧化酶的基因克隆及序列分析

Cloning and Sequencing of the Brazilian Banana Polyphenol Oxidase

基于香蕉基因组的信息,利用电子克隆方法获得巴西蕉PPO基因,结合RT-PCR验证,并通过生物信息学软件对巴西蕉PPO进行序列分析。结果表明,成功获得编码巴西蕉PPO的新基因,序列长度为1 767bp,编码588个氨基酸（Gen Bank登录号：KF900300.1）。巴西蕉PPO基因与禾本科植物PPO基因有着较高的同源性,相似度在82%~85%,与蔷薇科鸡麻亲缘关系最近。巴西蕉PPO最有可能存在于叶绿体中,不具有信号肽,含有一个长度为47个氨基酸的叶绿体转运肽。巴西蕉PPO蛋白属于酪氨酸酶基因家族蛋白,具有酪氨酸酶超级家族、PPO1_DWL和PPO1_KFDV3个保守结构域。巴西蕉PPO分子量为65.6 KDa,等电点为6.32,为亲水性蛋白质。巴西蕉PPO二级结构中无规则卷曲占的比例最高为57.31%,成功预测得到巴西蕉PPO的三级结构模型。

Based on the information about the banana genome,PPO gene of brazilian banana was cloned in silico,and validated by RT-PCR,and analyzed by bioinformatics software.New gene encoding brazilian banana PPO wassuccessfully obtained,with sequence length of 1767 bp,encoded a protein of 588 amino acids（Gen Bank accessionnumber：KF900300.1）.Brazilian banana PPO gene has a high homology with gramineae plant PPO gene,and theirsimilarity was between 82%~85%.Furthermore,brazilian banana PPO gene had the closest relationship with the rho-dotypos scandens of rosaceae PPO gene.Brazilian banana PPO was most likely to exist in the chloroplast,without asignal peptide,but containing a chloroplast transit peptide with length of 47 amino acids.Brazilian banana PPO pro-tein belonged to tyrosinase protein gene family,with three conserved domains of tyrosine enzyme superfamily,PPO1_DWL and PPO1_KFDV.Brazilian banana PPO with molecular weight of 65.6 KDa and an isoelectric point of6.32,was a hydrophilic protein.The secondary structure of brazilian banana PPO in the proportion of random coil ac-counted for up to 57.31%.And the tertiary structure of brazilian banana PPO was predicted successfully.