香港牡蛎(Crassostrea hongkongensis)新型凝集素ChPerlucin的基因克隆与功能研究

C-型凝集素(C-type lectin)是一类能识别并结合多糖的免疫蛋白质超家族, 本文首次克隆了一种新型香港牡蛎C-型凝集素基因——甘露聚糖结合凝集素, 并获得了该基因的全长序列, 命名为ChPerlucin。结果显示, ChPerlucin基因cDNA全长577bp, 包括21bp的5′末端非翻译区(untranslated region, UTR)、73bp的 3′UTR, 以及483bp的开放阅读框(open reading frame, ORF), 编码160个氨基酸, ChPerlucin蛋白理论分子量为18kD, 等电点为5.95。ChPerlucin蛋白含有保守的C-型凝集素样结构域(C-type lectin or carbohydrate-recognition domain, CLECT); 邻接法(Neighbor-Joining, NJ)进化树分析表明, ChPerlucin与其他贝类的Perlucin聚为一支, 说明该基因是软体动物Perlucin家族的新成员。qRT-PCR结果显示, ChPerlucin在香港牡蛎所检测组织和各个胚胎发育时期中均有表达; 病原菌刺激后, ChPerlucin表达量显著升高; 利用毕赤酵母真核成功表达了ChPerlucin重组蛋白, 发现ChPerlucin重组蛋白具有抑菌效果。以上结果表明ChPerlucin在香港牡蛎的先天性免疫过程中发挥了重要的作用。

Molecular cloning and functional studies of ChPerlucin in Crassostrea hongkongensis

The C-type lectin superfamily is a class of immune proteins that can recognize and bind to polysaccharides. In this study, a new type C-type lectin gene of Crassostrea hongkongensis was cloned for the first time, and the full-length sequence of the gene was obtained. The results show that the full length of ChPerlucin gene cDNA is 577 bp, including 5′-untranslated region (UTR) in 21 bp, 3′-UTR in 73 bp, and an open reading frame (ORF) in 483 bp open reading that code 160 amino-acid polypeptide. The predicted molecular mass is 18kD, and the isoelectric point is 5.95. Amino acid sequence alignment showed that the Perlucin gene of Crassostrea hongkongensis contains a conserved carbohydrate recognition domain (CLECT). Neighbor-Joining (NJ) evolutionary tree analysis showed that ChPerlucin clustered with Perlucin from other shellfish, indicating that this gene is a new member of the Perlucin family of mollusks. The results of qRT-PCR showed that ChPerlucin was broadly expressed in various tissues and during different stages of the oyster’s embryonic and larval development; the expression of ChPerlucin increased significantly after bacteria stimulation; the recombinant protein ChPerlucin was successfully expressed using Pichia pastoris eukaryotic; and we find that ChPerlucin recombinant protein has antibacterial effect. The above results indicate that ChPerlucin plays an important role in the innate immunity of Crassostrea hongkongensis.