半滑舌鳎黏蛋白MUC18基因克隆与序列分析

Cloning and Sequence Analysis of MUC18 Gene in Semi-smooth Tongue Sole, Cynoglossus semilaevis

采用RT-PCR方法扩增半滑舌鳎Cynoglossus semilaevis黏蛋白18基因(CsMUC18),对其结构、抗原表位、系统发育树等进行了生物信息学分析。结果表明,扩增获得CsMUC18基因片段长度为1 934bp,可编码635aa,预测含有1个信号肽(1~24aa)、1个跨膜区(560~582aa)、5个免疫球蛋白结构域(25~138、146~247、253~331、342~421和428~498aa)、7个主要抗原表位(67~79、172~177、218~225、552~558、593~605、613~618和628~635aa);二级结构预测CsMUC18以β折叠为主,其中跨膜区由α螺旋构成。Blastp分析显示CsMUC18与大菱鲆Scophthalmus maximus、斑马鱼Danio rerio MUC18序列同源性分别为61.31%和41.09%;系统发育树分析显示与鱼类膜结合型黏蛋白MUC18亲缘关系较近,自然聚为一支。本结果可为半滑舌鳎黏蛋白功能及其黏膜免疫应答机制研究提供参考。

In this study,the CsMUC18 gene of semi-smooth tongue sole Cynoglossus semilaevis was amplified by RT-PCR method,and the gene structure,antigenic epitope and phylogenetic tree were bioinformatically analysed.It was found that the fragment of CsMUC18 gene was 1934 bp in length,deduced coding 635 aa,and contained one signal peptide(position at 1~24 aa),a transmembrane region(560~582 aa),5 immunoglobulin domains(25~138,146~247,253~331,342~421 and 428~498 aa)and 7 major antigen epitopes(67~79,172~177,218~225,552~558,593~605,613~618 and 628~635 aa).The secondary structure of the CsMUC18 was dominated byβ-sheet and the transmembrane region was composed ofαhelix.The putative amino acid sequence of CsMUC18 shared the identities of 61.31%with the turbot(Scophthalmus maximus)and 41.09%with zebrafish(Danio rerio).Phylogenetic tree analysis revealed that CsMUC18 was closely related to the membrane-bound mucin MUC18 and naturally clustered into one group in fish.The results provide scientific references with further investigation of the mucin function and immune response mechanism of semi-smooth tongue sole.