Abstract：
LRR-only protein (LRRop) is an important class of immune molecules that function as pattern recognition receptor in invertebrates, however, the bacterial inhibitory activity of this proteins remain largely unknown. Herein, a novel LRRop was cloned from Eriocheir sinensis and named as EsLRRop2. The EsLRRop2 consists of six LRR motifs and formed a horseshoe shape three-dimension structure. EsLRRop2 was mainly expressed in intestine and hepatopancreas. The transcripts of EsLRRop2 in the intestine and hepatopancreas were induced by Vibrio parahaemolyticus and Staphylococcus aureus, and displayed similar transcriptional profiles. The expression levels of EsLRRop2 responded more rapidly and highly to V. parahaemolyticus than S. aureus in the intestine and hepatopancreas. Although the basal expression level of EsLRRop2 in hemocytes was relatively low, its transcripts in hemocytes were significantly induced by V. parahaemolyticus and S. aureus. The recombinant proteins of EsLRRop2 (rEsLRRop2) displayed a wide range of binding spectrum against vibrios, including V. parahaemolyticus, V. alginolyticus, and V. harveryi. The rEsLRRop2 showed dose- and time-dependent inhibitory activity against V. parahaemolyticus and S. aureus, and it could agglutinate the two bacteria. Furthermore, the inhibitory activities of rEsLRRop2 against V. parahaemolyticus, V. alginolyticus, V. harveryi and S. aureus was slightly affected by pH and salinity, and the rEsLRRop2 displayed the strongest inhibitory activity against all the three vibrios when the salinity was 20 ‰ and pH was 8.0. Collectively, these results elucidate the bacterial binding and inhibitory activities of EsLRRop2, and provide theoretical foundations for the application of rEsLRRop2 in prevention and control of vibrio diseases in aquaculture.
摘要：
LRR-only蛋白（LRRop）是一类重要的免疫分子，在无脊椎动物中充当模式识别受体，然而,这种蛋白质的细菌抑制活性仍然是未知的。在这里，从中华绒螯蟹中克隆了一个新的LRRop，命名为EsLRRrop2。EsLRRop2由六个LRR基序组成，并形成马蹄形三维结构。EsLRrop2主要在肠和肝胰腺中表达。EsLRop2在肠和肝胰腺中的转录本由副溶血性弧菌和金黄色葡萄球菌诱导，并显示相似的转录谱。在肠和肝胰腺中，EsLRRop2的表达水平对副溶血弧菌的反应比金黄色葡萄球菌更快，更高。尽管EsLRop2在血细胞中的基础表达水平相对较低,副溶血性弧菌和金黄色葡萄球菌显著诱导其在血细胞中的转录本。EsLRRop2（rEsLRRop2）的重组蛋白对弧菌具有广泛的结合谱，包括副溶血性弧菌，五、溶藻,还有V.Harveryi.rEsLRrop2对副溶血性弧菌和金黄色葡萄球菌显示出剂量和时间依赖性抑制活性，它可以凝集这两种细菌。此外，rEsLRRop2对副溶血性弧菌的抑制活性，五、溶藻,V.harveryi和金黄色葡萄球菌受pH和盐度的影响较小，当盐度为20‰，pH为8.0时，rEsLRRop2对所有三种弧菌均表现出最强的抑制活性。总的来说，这些结果阐明了EsLRrop2的细菌结合和抑制活性，为rEsLRrop2在水产养殖弧菌病防治中的应用提供了理论依据。
