松墨天牛铁蛋白重链相似物的cDNA克隆及生物信息学分析

cDNA cloning and bioinformatics of a ferritin heavy chain homologue from beetle, Monochamus alternatus

昆虫铁蛋白(ferritin)由两个亚基组成,类似于脊椎动物铁蛋白的重链和轻链。从松墨天牛(Monochamus alternatus)cDNA文库中筛选出ferritin基因的重链同源物(HCH)cDNA序列,其开放阅读框(ORF)长669 bp,编码222个氨基酸,命名为Mafer,GenBank登录号为KJ872588,该序列推测的蛋白分子质量为25.8 ku,等电点为5.72。预测的松墨天牛ferritin信号肽长度为18个氨基酸残基,在5′非编码区没发现铁反应元件(IRE),N末端有保守的半胱氨酸,符合脊椎动物重链特点。相似性比对显示,松墨天牛ferritin与光肩星天牛(Anoplophora glabripennis)和桑天牛(Apriona germari)ferritin的相似性分别为93%和69%;系统进化树分析显示,松墨天牛与光肩星天在同一分支下,与黑腹果蝇(Drosophila melanogaster)亲缘关系较远。

Insect ferritin is composed of two subunits, which are similar to heavy and light chains of vertebrate ferritins. A heavy chain homologue （HCH） cDNA of Monochamus alternatus, designated as Mafer （GenBank： KJ872588） was obtained from a previously constructed DNA library. The open reading frame of Mafer is 669 bp in length, encoding 222 amino acid residues with calculated molecular mass of 25.8 ku and isoeleetric point of 5.72. Among the predicted Mafer protein sequence, a 18 amino acid signal peptide and cysteine domain were found, wich is in accord with the HCH of vertebrates. But Mafer contains no iron responsive element （IRE） at its 5＇-UTR. The sequence alignment shows that Mafer has 93% and 69% identity with A noplophora glabripennis HCH and Apriona germari HCH, respectively. Phylogenetic analysis indicats that M. alternatus and A. glabripennis was on the same branch, and M. alternatus is distantly related with Drosophila melanogaster.