The Key Laboratory of Plant Cell Engineering and Germplasm Innovation of Ministry of Education, School of Life Sciences, Shandong University, Jinan, Shandong 250100, China.
Dev Comp Immunol. 2013 Jul-Aug;40(3-4):311-9. doi: 10.1016/j.dci.2013.03.011. Epub 2013 Mar 22.
Lysin domain (LysM) is a widely spread domain in nature and could bind different peptidoglycans and chitin-like compounds in bacteria and eukaryotes. In plants, Lysin motif containing proteins are one of the major classes of pattern recognition proteins which can recognize GlcNAc-containing glycans and have important functions in plant immunity. However, their functions in animal immunity are still unclear. In this study, a cDNA encoding a LysM containing protein was identified from red swamp crayfish, Procambarus clarkii. The cDNA of PcLysM contained 1200 base pair nucleotides with an open reading frame of 702bp encoding a protein of 233 amino acid residues. The deduced protein had a calculated molecular mass of 25.950kDa and a pI of 6.84. Tissue distribution analysis in mRNA level showed that it was highly expressed in gills, hemocytes, and intestine, and lowly expressed in hearts, hepatopancreas, and stomach. Time course expression pattern analysis showed that PcLysM was upregulated in hemocytes and gills after challenge with Vibrio anguillarum, and it was upregulated at 12h after challenge with Staphylococcus aureus in gills. The recombinant PcLysM could bind to different bacteria, and yeast. Further study revealed that PcLysM could bind to peptidoglycans from different bacteria, and chitin. After PcLysM was knocked down, the upregulation of antimicrobial peptide (AMP) genes (crustins and antilipopolysaccharide factors) was suppressed in response to bacterial infection in gills. These results suggest that PcLysM recognizes different microorganisms through binding to polysaccharides, such as peptidoglycans and chitin and regulates the expression of some antimicrobial peptide genes though unknown pathways and regulates the expression of some antimicrobial peptide genes though unknown pathways. This study might provide a clue to elucidate the roles of PcLysM in the innate immune reaction of crayfish P. clarkii.
几丁质结合域（LysM）在自然界中广泛存在，能够结合细菌和真核生物中的不同肽聚糖和几丁质样化合物。在植物中，含有赖氨酸基序的蛋白是模式识别蛋白的主要类别之一，能够识别含有 GlcNAc 的糖，并在植物免疫中具有重要功能。然而，它们在动物免疫中的功能仍不清楚。本研究从克氏原螯虾（Procambarus clarkii）中鉴定出一种含有几丁质结合域的 cDNA。PcLysM 的 cDNA 包含 1200 个碱基对核苷酸，开放阅读框为 702bp，编码 233 个氨基酸残基的蛋白质。推导的蛋白质具有 25.950kDa 的计算分子质量和 6.84 的 pI。在 mRNA 水平的组织分布分析表明，它在鳃、血细胞和肠组织中高度表达，在心、肝胰腺和胃组织中低表达。时间过程表达模式分析表明，PcLysM 在受到鳗弧菌刺激后在血细胞和鳃中上调，在受到金黄色葡萄球菌刺激后 12 小时在鳃中上调。重组 PcLysM 可以与不同的细菌和酵母结合。进一步的研究表明，PcLysM 可以与不同细菌的肽聚糖和几丁质结合。在 PcLysM 被敲低后，在鳃中对细菌感染的反应中，抗菌肽（Crustin 和抗脂多糖因子）基因的上调受到抑制。这些结果表明，PcLysM 通过与多糖（如肽聚糖和几丁质）结合来识别不同的微生物，并通过未知途径调节一些抗菌肽基因的表达。本研究可能为阐明 PcLysM 在克氏原螯虾 P. clarkii 先天免疫反应中的作用提供线索。
