Identification, expression analysis, and antibacterial activity of NK-lysin from common carp Cyprinus carpio
Identification, expression analysis, and antibacterial activity of NK-lysin from common carp Cyprinus carpio
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鲤鱼NK-lysin的鉴定、表达分析及抑菌活性
DOI：
10.1016/j.fsi.2017.11.030
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发表时间：
2018-02-01
影响因子：
4.7
通讯作者：
Xie, Hai Xia
中科院分区：
文献类型：
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作者：
Wang, Gai Ling;Wang, Ming Cheng;Xie, Hai Xia
自然杀伤细胞溶素（NK-lysin）由细胞毒性T淋巴细胞和自然杀伤细胞产生，是一种阳离子抗菌肽，具有广泛的抗菌谱，包括细菌、病毒和寄生虫。然而，NK-赖氨酸在防止细菌感染方面的作用在鲤鱼中尚不清楚。在这项研究中，在鲤鱼基因组中鉴定出了六种不同的 NK-溶素基因（nkl1、nkl2、nkl3、nkl4、nkl5 和 nkl6）。鲤鱼 NK 溶素的每个成熟肽都具有 6 个高度保守的半胱氨酸残基，并共享一个 Saposin B 结构域，这是 Saposin 样蛋白 (SAID) 家族的特征。基因nkl1含有5个外显子和4个内含子，nkl2、nkl3、nkl4或nk15含有4个外显子和3个内含子，而nkl6含有3个外显子和2个内含子。通过实时定量PCR，nkl2转录本主要在健康鲤鱼的脾脏中表达，而在嗜水气单胞菌感染后主要在鳃和脾脏中表达升高。从毕赤酵母中纯化的重组NK-lysin-2对金黄色葡萄球菌（革兰氏阳性）、埃希氏菌M15、嗜水气单胞菌以及迟缓爱德华氏菌（革兰氏阴性）具有抗菌活性，后两者是水产养殖的重要病原体。我们的研究结果表明，鲤鱼中的 NK-赖氨酸可能通过增强针对细菌病原体的抗菌防御，在鱼类免疫反应中发挥重要作用。
Natural killer lysin (NK-lysin), produced by cytotoxic T lymphocytes and natural killer cells, is a cationic antimicrobial peptide that has a broad antimicrobial spectrum, including bacteria, viruses, and parasites. Nevertheless, the implication of NK-lysin in the protection against bacterial infection is not aware in common carp. In this study, six different NK-Iysin genes (nkl1, nkl2, nkI3, nkl4, nkl5 and nkl6) were identified in the common carp genome. Each of the mature peptides of common carp NK-lysin has six well-conserved cysteine residues, and shares a Saposin B domain, characteristic of saposin-like protein (SAID) family. The gene nkl1 contains 5 extrons and 4 introns, and nkl2, nkl3, nkl4 or nk15 contains 4 extrons and 3 introns, however, the nkl6 has 3 extrons and 2 introns. By quantitative real-time PCR, nkl2 transcripts were predominantly expressed in spleen of healthy common carp, while elevated mainly in gill and spleen upon Aeromonas hydrophila infection. The recombinant NK-lysin-2 purified from Pichia pastoris shows antibacterial activity against Staphylococcus aureus (Gram-positive), and Escherkhia coil M15, Aeromonas hydrophila, as well as Edwardsiella tarda (Gram-negative), the latter two are important pathogens of aquaculture. Our results indicate that NK-lysin in common carp might play an important role in fish immune response by enhancing antibacterial defense against bacterial pathogens.