A novel C-type lectin with two CRD domains from Chinese shrimp Fenneropenaeus chinensis functions as a pattern recognition protein.
A novel C-type lectin with two CRD domains from Chinese shrimp Fenneropenaeus chinensis functions as a pattern recognition protein.
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DOI：
10.1016/j.molimm.2009.02.029
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发表时间：
2009-05
影响因子：
3.6
通讯作者：
Xiao-Wen Zhang;Wen-Teng Xu;Xian-Wei Wang;Y. Mu;Xiao-Fan Zhao;Xiao-qiang Yu;Jin-Xing Wang
中科院分区：
文献类型：
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作者：
Xiao-Wen Zhang;Wen-Teng Xu;Xian-Wei Wang;Y. Mu;Xiao-Fan Zhao;Xiao-qiang Yu;Jin-Xing Wang
凝集素被认为是潜在的免疫识别蛋白。本研究从中国对虾（Fenneropenaeus chinensis）肝胰腺中克隆了一种新型c型凝集素（Fc-Lec2）。Fc-Lec2 cDNA全长1219bp， ORF全长1002bp，编码333个氨基酸的蛋白。Fc-Lec2含有一个信号肽和两个不同的碳水化合物识别结构域（CRDs）。第一个CRD包含一个QPD （Gln-Pro-Asp）基序，该基序对半乳糖具有预测的结合特异性，第二个CRD包含一个EPN （gln - pro - asn）基序对甘露糖具有结合特异性。Fc-Lec2在正常对虾的肝胰脏中组成性表达，在细菌或病毒侵染对虾的肝胰脏中表达上调。重组成熟Fc-Lec2及其两个单独的crd （CRD1和2）对动物红细胞不具有血凝活性，但以钙依赖的方式凝集了一些革兰氏阳性和革兰氏阴性细菌。这三种重组蛋白在缺乏钙的情况下也能与细菌结合。Fc-Lec2似乎对细菌和多糖（肽聚糖、脂质胆酸和脂多糖）具有更广泛的特异性和更高的亲和力，而不是两种单独的crd。这些数据表明，两个CRDs具有协同作用，完整的凝集素可能更有效地响应细菌感染，Fc-Lec2通过与病原体细胞的多糖结合来发挥其模式识别功能。
Lectins are regarded as potential immune recognition proteins. In this study, a novel C-type lectin (Fc-Lec2) was cloned from the hepatopancreas of Chinese shrimp, Fenneropenaeus chinensis. The cDNA of Fc-Lec2 is 1219bp with an open reading frame (ORF) of 1002bp that encodes a protein of 333 amino acids. Fc-Lec2 contains a signal peptide and two different carbohydrate recognition domains (CRDs) arranged in tandem. The first CRD contains a QPD (Gln-Pro-Asp) motif that has a predicted binding specificity for galactose and the second CRD contains a EPN (Glu-Pro-Asn) motif for mannose. Fc-Lec2 was constitutively expressed in the hepatopancreas of normal shrimp, and its expression was up-regulated in the hepatopancreas of shrimp challenged with bacteria or viruses. Recombinant mature Fc-Lec2 and its two individual CRDs (CRD1 and 2) did not have hemagglutinating activity against animal red blood cells, but agglutinated some Gram-positive and Gram-negative bacteria in a calcium-dependent manner. The three recombinant proteins also bound to bacteria in the absence of calcium. Fc-Lec2 seems to have broader specificity and higher affinity for bacteria and polysaccharides (peptidoglycan, lipoteichoic acid and lipopolysaccharide) than each of the two individual CRDs. These data suggest that the two CRDs have synergistic effect, and the intact lectin may be more effective in response to bacterial infection, the Fc-Lec2 performs its pattern recognition function by binding to polysaccharides of pathogen cells.