气孔蛋白同源物在单、双子叶植物中的生物信息学分析

本文对NCBI数据库中的4种单子叶植物（玉米，高粱，水稻和二穗短柄草）和5种双子叶植物（筷子芥，大豆，蒺藜苜蓿，毛果杨和蓖麻）的气孔蛋白同源物，利用生物信息学分析工具在基因结构、碱基组成、氨基酸理化性质、信号肽结构、磷酸化位点、二级结构及三维结构上进行了比较分析，并构建系统进化树。结果表明，单、双子叶植物中的气孔蛋白同源物在基因结构上均由3个外显子和2个内含子构成；编码的蛋白均属于不稳定的疏水性蛋白，且存在信号肽结构和C端保守的6个半胱氨酸残基；在保守的成熟肽区段含有酪蛋白激酶Ⅱ磷酸化位点（T），不含α-螺旋结构，但三维结构基本一致。它们之间的不同点如下：单子叶植物气孔蛋白同源物在基因结构上存在一致的上游同框终止密码子，且G-C含量高于双子叶植物，而AT含量低于双子叶植物；单子叶植物中气孔蛋白同源物的氨基酸残基数目较庞大（除大豆外），在前肽和信号肽区域分别含有相对保守的酪蛋白激酶Ⅱ磷酸化位点（S）和N端豆蔻酰化位点；二级结构中的延伸折叠结构和任意卷曲结构分别多于和少于双子叶植物。系统进化树表明，气孔蛋白在单子叶作物和双子叶植物之间产生了进化上的差异。气孔蛋白同源物在单、双子叶植物中存在明显的差异，这可能与基因的表达调控以及蛋白功能的活化机制有关。但是否与单、双子叶植物表皮细胞气孔的形态差异有关仍待进一步的研究。

Bioinformatics Analysis of Stomagen Orthologs beween Monocotyledons and Dicotyledons

Orthologs ofstomagen for 4 monocotyledons （com, sorghum, rice and two ears of Brachypodium） and 5 dicotyledons （mustard, soybean, Medicago truncatula, Populus trichocarpa and castor） were analyzed in in gene structure, base composition, amino acid physico-chemical properties, signal peptide, phosphorylation sites, sec- ondary structure and three-dimensional structure, using bioinformatics analysis tools, and the phylogenetic tree was constructured. The results showed that the gene structure of stomagen orthologs is composed of 3 exons and 2 introns for monocotyledons and dicotyledons, who encode an unstable and hydrophobic protein, with one signal peptide structure and C-terminal six conserved cysteine residues; casein kinase II phosphorylation site （T） occurs in the mature peptide segment conservatively; the three-dimensional structure of stomagen orthologs is basically consistent, but flee of a-helix. The differences among them are as follows： the stomagen orthologs of mono- cotyledons are consistent in existing upstream in-flame stop codon in genetic structure; GC contents of mono- cotyledons are higher while AT contents are lower than that of dicotyledons; the number of amino acid residues forstomagen orthologs are larger in monocotyledons （except soybean）; in the propeptide and signal peptide region of monocotyledonsthere areone or two relatively conservative casein kinase n phosphorylation sites （S） andN-myris- toylation sites, respectively; the number of extended strend and random coil in monocotyledons are more than and less than that of dicotyledons, respectively. Phylogenetic tree showed that stomagen orthologs generated evolutionary differences between monocotyledons and dicotyledons, the inductions of which may be related to the mechanism of gene-expressional regulation and protein-functional activation. However, whethe the differences of stomagen orthologs are related to the morphological differences of epidermal stomatal complex between monocotyledons and dicotyledons or not still needs further study.