温世杰+李杏瑜+洪彦彬+李少雄+周桂元+陈小平+梁炫强

摘 要 植物中的Δ12脂肪酸脱氢酶（FAD2）是油酸形成亚油酸的关键酶。通过NCBI和EXPASY 2大数据库，采用SignalP、TMHMM、Psort、ProtParam和TargetP等分析程序对花生品种‘航花2号及其它物种的19个FAD2蛋白序列进行分析，利用MEGA6.0软件比对序列及构建系统进化树阐明FAD2基因的系统发育关系，亲缘相近的FAD2蛋白聚在一起。预测了‘航花2号和‘粤油13的FAD2蛋白的分子质量、等电点、信号肽、跨膜和保守结构域等。结果表明：‘航花2号FAD2蛋白的N端没有信号肽，预测定位在微体、细胞质、线粒体基质和叶绿体类囊膜中，而C端信号基序LKGL使得FAD2蛋白选择性地结合和嵌入内质网，植物的FAD2蛋白普遍有3个高度保守的组氨酸富集基序（HECGHH、HRRHH和H[A/C/T]HH）和3～5个跨膜结构，但分析结果显示，‘航花2号的FAD2蛋白的H[A/C/T]HH的组氨酸基序是缺失的，而油酸转化为亚油酸的效率上并没有显著变化，为将来FAD2基因的基因工程操作提供一定的理论基础。

关键词 花生 ；脂肪酸脱氢酶 ；生物信息学 ；油料作物

中图分类号 Q946.81 文献标识码 A Doi：10.12008/j.issn.1009-2196.2017.09.008

Bioinformatic Analysis of Delta-12 Fatty Acid Desaturase 2（FAD2）

WEN Shijie LI Xingyu HONG Yanbin LI Shaoxiong

ZHOU Guiyuan CHEN Xiaopin LIANG Xuanqiang

（Crops Research Institute， Guangdong Academy of Agricultural Sciences / Guangdong Key

Laboratory for Crops Genetic Improvement / South China Peanut Sub-Center of National

Center of Oilseed Crops Improvement， Guangzhou， Guangdong 510640）

Abstract Delta-12 fatty acid desaturase 2 （FAD2） was a key enzyme to insert oleic acid to linoleic acid. Through the NCBI and EXPASY 2 database， nineteen FAD2 protein sequences from peanut Hanghua 2 and other species of plants were analyzed by SignalP， TMHMM， Psort， ProtParam and TargetP procedures. The phylogenetic relationship of FAD2 was elucidated by neighbour-joining tree and MEGA6.0. FAD2 proteins with high similarity sequence were clustered. The molecular mass， isoelectric point， signal peptide， trans-membrane and conserved domains of FAD2 protein were predicted for peanut Hanghua 2 and Yueyou 13. The results showed that there was no signal peptide of N-terminal of FAD2 in Huanghua 2. The FAD2 proteins were predicted in microbody， cytoplasm， mitochondrial matrix space and chloroplast thylakoid membrane. C-terminal signaling motif LKGL allows FAD2 proteins to selectively bind and embed in the endoplasmic reticulum. The FAD2 proteins included three highly conserved histidine-rich motifs （HECHH， HRRHH and HV[A/C/T]HH） and three to five transmembrane anchors. But C-terminal of FAD2 in Huanghua 2 was lack of HV[A/C/T]HH histidine motif. No change was observed in efficiency of insertion of oleic acid to linoleic acid. This could be used for genetic engineering of FAD2 gene in the future.

Keywords peanut ； fatty acid desaturase ； bioinformatics ； oilseed crops

油料作物是人類重要的食材之一[1]，同时也被广泛用于医药、化妆、乳化剂等领域，是重要的经济作物[2-3]。油料作物中，脂肪酸是种子的主要贮存脂质和重要的能量来源。脂肪酸脱氢酶在脂肪酸代谢过程中起着在烃链中引入双键的功能。脂肪酸脱氢酸分成两类，一类是可溶性蛋白脱氢酶（ACP-desaturas），另一类是膜结合脂肪酸脱氢酶。质体中的脱氢酶的电子供体通常是铁氧化还原蛋白，而内质网的脱氢酶则是细胞色素b5[4]，质体和内质网中发生的脱氢反应是通过2种不同的途径发生的[5]。……