Identification and characterization of a laccase from Litopenaeus vannamei involved in anti‐bacterial host defense
Identification and characterization of a laccase from Litopenaeus vannamei involved in anti‐bacterial host defense
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DOI：
10.1016/j.fsi.2017.04.026
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发表时间：
2017-07
影响因子：
4.7
通讯作者：
Lili Shi;S. Chan;Chaozheng Li;Shuang Zhang
中科院分区：
文献类型：
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作者：
Lili Shi;S. Chan;Chaozheng Li;Shuang Zhang
酚氧化酶（Phenoloxidases，PO）是一类重要的生物酶，包括酪氨酸酶、儿茶酚酶和漆酶，在多种无脊椎动物的免疫防御中起重要作用。对虾体内是否存在漆酶及其功能尚不清楚。本研究首次从凡纳滨对虾（Litopenaeus vannamei）中克隆并鉴定了一种漆酶（LvLac）。LvLac基因全长3406 bp，包括一个2034 bp的开放阅读框（ORF），编码677个氨基酸，信号肽33个氨基酸。LvLac包含三个铜氧化酶结构域，其铜结合中心分别由10个组氨酸、1个半胱氨酸和1个甲硫氨酸形成。系统进化分析表明，LvLac与昆虫漆酶1家族关系密切。LvLac在心脏中表达量最高，且LvLac粗蛋白能催化氢醌的氧化。实时荧光定量PCR结果表明，LvLac基因表达对副溶血性弧菌、溶壁微球菌和白色斑点综合征病毒（WSSV）感染有反应。敲低LvLac基因可增强对虾对副溶血性弧菌和溶壁支原体攻击的敏感性，提示LvLac可能对细菌性病原体具有积极的抵抗作用。
Phenoloxidases (POs) are a family of enzymes including tyrosinases, catecholases and laccases, which play an important role in immune defences of various invertebrates. Whether or not laccase exists in shrimp and its function is still poorly understood. In this study, a laccase (LvLac) was cloned and identified from Litopenaeus vannamei for the first time. The full length of LvLac is 3406 bp, including a 2034 bp open reading frame (ORF) coding for a putative protein of 677 amino acids with a signal peptide of 33 aa. LvLac contains three Cu-oxidase domains with copper binding centers formed by 10 histidines, one cysteine and one methionine, respectively. Phylogenetic analysis revealed that LvLac was close to insects laccase 1 family. LvLac expression was most abundant in heart and the crude LvLac protein could catalyze the oxidation of hydroquinone. Real-time PCR showed that LvLac expression was responsive to Vibrio parahaemolyticus, Micrococcus lysodeikticus and white spot syndrome virus (WSSV) infection. Knockdown of LvLac enhanced the sensitivity of shrimps toV. parahaemolyticusandM. lysodeikticuschallenge, suggesting that LvLac may play a positive role against bacterial pathogens.