Zhang Ying, Qiu Limei, Song Linsheng, Zhang Huan, Zhao Jianmin, Wang Lingling, Yu Yundong, Li Chenghua, Li Fengmei, Xing Kezhi, Huang Bingxin
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
Fish Shellfish Immunol. 2009 Jan;26(1):183-92. doi: 10.1016/j.fsi.2008.03.008. Epub 2008 Mar 26.
In invertebrates, C-type lectins play crucial roles in innate immunity responses by mediating the recognition of host cells to pathogens and clearing microinvaders, which interact with carbohydrates and function as pattern recognition receptors (PRRs). A novel C-type lectin gene (LvLec) cDNA was cloned from hemocytes of Litopenaeus vannamei by expressed sequence tag (EST) and rapid amplification of cDNA ends (RACE) PCR. The full-length cDNA of LvLec was of 618 bp, consisting of a 5'-terminal untranslated region (UTR) of 60 bp and a 3'-UTR of 87 bp with a poly (A) tail. The deduced amino acid sequence of LvLec possessed all conserved features critical for the fundamental structure, such as the four cysteine residues (Cys(53), Cys(128), Cys(144), Cys(152)) involved in the formation of disulfides bridges and the potential Ca(2+)/carbohydrate-binding sites. The high similarity and the close phylogenetic relationship of LvLec shared with C-type lectins from vertebrates and invertebrates. The structural features of LvLec indicated that it was an invertebrate counterpart of the C-type lectin family. The cDNA fragment encoding the mature peptide of LvLec was recombined and expressed in Escherichia coli BL21(DE3)-pLysS. The recombinant protein (rLvLec) could agglutinate bacteria E. coli JM109 depending on Ca(2+), and the agglutination could be inhibited by mannose and EDTA. These results indicated that LvLec was a new member of C-type lectin family and involved in the immune defence response to Gram negative bacteria in Litopenaeus vannamei.
在无脊椎动物中，C型凝集素通过介导宿主细胞对病原体的识别以及清除微小入侵者，在先天免疫反应中发挥关键作用，这些微小入侵者与碳水化合物相互作用并作为模式识别受体（PRR）发挥功能。通过表达序列标签（EST）和cDNA末端快速扩增（RACE）PCR技术，从凡纳滨对虾的血细胞中克隆出一个新的C型凝集素基因（LvLec）的cDNA。LvLec的全长cDNA为618 bp，由一个60 bp的5'-末端非翻译区（UTR）和一个带有poly（A）尾的87 bp的3'-UTR组成。推导的LvLec氨基酸序列具有对基本结构至关重要的所有保守特征，例如参与二硫键形成的四个半胱氨酸残基（Cys(53)、Cys(128)、Cys(144)、Cys(152)）以及潜在的Ca(2+)/碳水化合物结合位点。LvLec与脊椎动物和无脊椎动物的C型凝集素具有高度相似性和密切的系统发育关系。LvLec的结构特征表明它是C型凝集素家族的无脊椎动物对应物。编码LvLec成熟肽的cDNA片段在大肠杆菌BL21(DE3)-pLysS中进行重组表达。重组蛋白（rLvLec）能够在Ca(2+)存在的情况下凝集大肠杆菌JM109，并且这种凝集作用可以被甘露糖和EDTA抑制。这些结果表明LvLec是C型凝集素家族的一个新成员，并参与凡纳滨对虾对革兰氏阴性菌的免疫防御反应。
