Identification and molecular analysis of a novel C-type lectin from Scophthalmus maximus.
Identification and molecular analysis of a novel C-type lectin from Scophthalmus maximus.
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DOI：
10.1016/j.fsi.2010.02.023
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发表时间：
2010-07
影响因子：
4.7
通讯作者：
M. Zhang;Yong-hua Hu;Li Sun
中科院分区：
文献类型：
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作者：
M. Zhang;Yong-hua Hu;Li Sun
C 型凝集素是钙依赖性碳水化合物结合蛋白，在先天免疫中发挥重要作用。在本研究中，从大菱鲆中鉴定出 C 型凝集素同源物 (SmLec1)，并在表达和功能水平上进行了分析。 SmLec1的开放阅读框为504 bp，其中5′-非翻译区(UTR)为101 bp，3′-UTR为164 bp。推导的 SmLec1 氨基酸序列与多种鱼类的 C 型凝集素具有 34%–38% 的总体同一性。计算机分析鉴定出 SmLec1 保守的 C 型凝集素特征，包括碳水化合物识别结构域、四个二硫键形成半胱氨酸残基和甘露糖型碳水化合物结合基序。此外，SmLec1 拥有推定的信号肽序列，预计位于细胞外。 SmLec1 在肝脏中的表达最高，并对鱼类病原体的实验挑战做出积极反应。从酵母中纯化的重组 SmLec1 (rSmLec1) 能够凝集革兰氏阴性鱼类病原体鳗鱼利斯顿氏菌，但不能凝集革兰氏阳性病原体海豚链球菌。 rSmLec1 的凝集能力在甘露糖和乙二胺四乙酸存在下以及升高温度 (65 °C) 时被消除。进一步分析表明，rSmLec1可以刺激肾脏淋巴细胞增殖，增强巨噬细胞对细菌病原体的杀伤力。综上所述，这些结果表明 SmLec1 是一种独特的甘露糖结合 C 型凝集素，具有明显的免疫调节特性，并且可能参与宿主针对细菌感染的防御。
C-type lectins are calcium-dependent carbohydrate-binding proteins that play important roles in innate immunity. In this study, a C-type lectin homologue (SmLec1) was identified from turbot (Scophthalmus maximus) and analyzed at expression and functional levels. The open reading frame of SmLec1 is 504 bp, with a 5′-untranslated region (UTR) of 101 bp and a 3′-UTR of 164 bp. The deduced amino acid sequence of SmLec1 shares 34%–38% overall identities with the C-type lectins of several fish species. In silico analysis identified in SmLec1 conserved C-type lectin features, including a carbohydrate-recognition domain, four disulfide bond-forming cysteine residues, and the mannose-type carbohydrate-binding motif. In addition, SmLec1 possesses a putative signal peptide sequence and is predicted to be localized in the extracellular. Expression of SmLec1 was highest in liver and responded positively to experimental challenges with fish pathogens. Recombinant SmLec1 (rSmLec1) purified from yeast was able to agglutinate the Gram-negative fish pathogen Listonella anguillarum but not the Gram-positive pathogen Streptococcus iniae. The agglutinating ability of rSmLec1 was abolished in the presence of mannose and ethylenediaminetetraacetic acid and by elevated temperature (65 °C). Further analysis showed that rSmLec1 could stimulate kidney lymphocyte proliferation and enhance the killing of bacterial pathogen by macrophages. Taken together, these results suggest that SmLec1 is a unique mannose-binding C-type lectin that possesses apparent immunomodulating property and is likely to be involved in host defense against bacterial infection.