植物磷酸乙醇胺甲基转移酶的生物信息学分析

Bioinformatics Analysis of Phosphoethanolamine N-methyltransferase in Plants

运用生物信息学的方法,对已在Genbank数据库中注册的菠菜、甜菜、拟南芥、陆地棉和辽宁碱蓬等中磷酸胆碱合成的关键酶磷酸乙醇胺甲基转移酶(PEAMT)的氨基酸序列进行分析。结果显示:植物PEAMT属于稳定蛋白质,含有较丰富的赖氨酸和亮氨酸;不同植物PEAMT的氨基酸序列具有较高的同源性,含有与SAM结合的保守结合域及Tyr-His氨基酸对;植物PEAMT属于胞质酶,不与膜结合;分子进化研究表明PEAMT可作为植物遗传分化和分子进化研究的重要依据;氨基酸序列中不存在信号肽;分子中不存在跨膜结构域,可能受蛋白激酶C的磷酸化;无规则卷曲是多肽链中的主要结构元件;蛋白质保守区域包含两个AdoMet-MTase区域,属于典型的SAM依赖性甲基转移酶功能结构域。本研究还初步构建了菠菜PEAMT的三维模型,能够认识植物中PEAMT的特异性及催化分子机制,并为通过分子改造创造出具有更强抗逆效能的PEAMT提供理论参考。

Bioinformaties methods were employed to analyze amino acid sequences of phosphoethanolamine methyltransferase （PEAMT）, a key enzyme involved in the process of choline phosphate synthesis from Spinacia oleracea, Beta vulgaris, Atriplex hortensis, Gossypium hirsu-tum, Suaeda liaotungensis, etc. The results were as follows： PEAMTs were stable proteins. Lys and Leu were abundant in those PEAMTs. Sequence alignment revealed that PEAMTs were highly homologous in different plants, and the residues involved with function were very con-servative. PEAMTs were found to be targeted in cytoplasm. PEAMTs could be used as genetic differentiation and an important basis for the study of molecular evolution. There was no signal peptide in segnental plants. PEAMTs had no tmnsmembrane structure and could be phos-phorylated by protein kinase C. Random coil were the major structural element of polypeptide chain. Meanwhile, PEAMTs contained typical function domains of SAM dependent Methyltransferase. In addition, this study obtained the initial three-dimensional model of PEAMT from spinach, which supplied more information about the specificity and catalytic mechanism of PEAMT in plants, and provided theoretical refer- ence for plant resistance to environmental stress.