Liu Yan, Zhang Ying-Hao, Li Tong, Cao Xiao-Tong, Zhou Yang, Yuan Jun-Fa, Gu Ze-Mao, Lan Jiang-Feng
Department of Aquatic Animal Medicine, Research Center for Marine Biology, Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
College of Science, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
Dev Comp Immunol. 2018 Oct;87:109-115. doi: 10.1016/j.dci.2018.05.020. Epub 2018 May 31.
Antimicrobial peptides (AMPs) play important roles in innate immunity against pathogens and lysozymes are a particularly type of AMP. Lysozymes are hydrolytic enzymes that are characterized by their ability to cleave the beta-(1,4)-glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycan, which is the major bacterial cell wall polymer. In this work, a lysozyme was identified from Procambarus clarkii and designated PcLys-i3. Quantitative RT-PCR was used to analyze the tissue distribution and expression profiles of PcLys-i3. PcLys-i3 was present in all tested tissues and had high expression levels in gills, stomach and intestine. The expression levels of PcLys-i3 were up-regulated in gills and intestine after challenge with Vibrio parahaemolyticus, Staphylococcus aureus and Aeromonas hydrophila. PcLys-i3 and PcFer proteins can enhance the bacterial elimination in crayfish, whereas the bacterial elimination was weakened when the expression level of PcLys-i3 or PcFer RNAs was suppressed by RNAi. Recombinant PcLys-i3 and PcFer significantly reduced the mortality of crayfish with bacterial infections. Further study found that PcLys-i3 could interact with PcFer in vitro. Finally, the PcLys-i3 and PcFer proteins could bind to bacteria and inhibit bacterial replication. These results suggest that both PcLys-i3 and PcFer play important roles in the antibacterial immunity of red swamp crayfish.
抗菌肽（AMPs）在针对病原体的先天免疫中发挥着重要作用，而溶菌酶是一种特殊类型的抗菌肽。溶菌酶是水解酶，其特点是能够裂解肽聚糖中N - 乙酰胞壁酸和N - 乙酰葡糖胺之间的β-（1,4）-糖苷键，肽聚糖是细菌细胞壁的主要聚合物。在这项研究中，从克氏原螯虾中鉴定出一种溶菌酶，并命名为PcLys - i3。采用定量RT - PCR分析PcLys - i3的组织分布和表达谱。PcLys - i3存在于所有测试组织中，在鳃、胃和肠道中表达水平较高。在用副溶血性弧菌、金黄色葡萄球菌和嗜水气单胞菌攻击后，鳃和肠道中PcLys - i3的表达水平上调。PcLys - i3和PcFer蛋白可以增强小龙虾体内细菌的清除，而当通过RNA干扰抑制PcLys - i3或PcFer RNA的表达水平时，细菌清除能力减弱。重组PcLys - i3和PcFer显著降低了小龙虾细菌感染的死亡率。进一步研究发现，PcLys - i3在体外可与PcFer相互作用。最后，PcLys - i3和PcFer蛋白可结合细菌并抑制细菌复制。这些结果表明，PcLys - i3和PcFer在红螯螯虾的抗菌免疫中均发挥重要作用。
