致倦库蚊Cecropin基因家族的比较和系统发育分析

Comparative and Phylogenetic Analysis of Cecropin Gene Family in Culex quinquefasciatus

利用生物信息学方法比较分析了致倦库蚊Cecropin家族4成员的基因结构、氨基酸序列、蛋白理化特性,预测蛋白空间结构,并基于7种昆虫绘制分子进化树,随后使用RT-PCR方法获取致倦库蚊Cecropin家族4成员的c DNA。结果表明：致倦库蚊Cecropin家族基因有两条正向编码,两条反向编码,长度为330~544 bp,由2个外显子和1个内含子构成;氨基酸序列长度为59~61 aa,具有两条基序和多个保守位点;编码的蛋白理论分子量为6 284.6~6 619.0 k D,p I值为10.36~11.24,亲水性平均系数为0.393~0.551;蛋白预测的二级结构和三级结构结果基本一致,它们具有1个信号肽结构域和1个催化结构域,结构域主要由α-螺旋构成;7种昆虫的Cecropin蛋白进化关系与物种进化关系基本一致,并以“目”或“亚目”为单位分别聚类,CPIJ005108与致倦库蚊Cecropin祖先基因最相似。本研究的分析结果可为蚊科Cecropin结构和功能的研究提供有价值的信息。

The gene structures, amino acid sequences, protein physicochemical characteristics, protein senior structures of 4 Cecropin family members in Culex quinquefascicttus were compared and analyzed via bioinformatics methods, then the phylogenetic tree of Cecropin proteins was made based on 7 insects; Finally 4 Cecropin cDNA in C. quinquefasciatus were cloned by RT-PCR. The results indicated that Cecropin family genes have two forward coding and two reverse coding. All the 4 genes had the length of330-544 bp, and they were contained with two exons and one intron. Cecropin gene encoded a 59-61 amino acid peptide and included two motif as well as several conservative sites. The theoretical Cecropin protein had the molecular weight of 6 284.6-6 619.0, the pI of 10.36-11.24, and the GRAVY of 0.393-0.551. The predicted result for secondary structures of Cecropin proteins were consistent with their result for tertiary structure, that both composed with one signal peptide and one catalytic domain which formed by eL-helix mainly. The phylogenetic tree showed a positive correlation between Cecropin proteins and species, in which Cecropin proteins clustered according to ORDER or SUB-ORDER. Gene CPIJ005108 may be the most similar to the ancestral gene among the Cecropin family in C. quinquefctsciatus. Our study would provide valuable information for structural and functional research of Cecropin in the whole Diptera Culicidae.