Ostrinia furnacalis serpin-3 regulates melanization cascade by inhibiting a prophenoloxidase-activating protease
Ostrinia furnacalis serpin-3 regulates melanization cascade by inhibiting a prophenoloxidase-activating protease
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亚洲玉米螟 serpin-3 通过抑制原酚氧化酶激活蛋白酶来调节黑化级联
DOI：
10.1016/j.ibmb.2015.03.007
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发表时间：
2015-06-01
影响因子：
3.8
通讯作者：
An, Chunju
中科院分区：
文献类型：
--
作者：
Chu, Yuan;Zhou, Fan;An, Chunju
丝氨酸蛋白酶级联介导的酚氧化酶原激活是昆虫防御入侵病原体的一种重要的天然免疫反应。丝氨酸蛋白酶抑制剂调节该反应以避免过度活化。然而，丝氨酸蛋白酶抑制剂在大多数昆虫物种中的功能，特别是在一些非模式农业害虫中，在很大程度上是未知的。我们克隆了亚洲玉米螟Ostrinia furnacalis（Guenee）的serpin全长cDNA，命名为serpin-3。丝氨酸蛋白酶抑制剂3的开放阅读框架编码462个氨基酸残基的蛋白质，其中含有19个残基的信号肽。它含有一个反应中心环，与酚氧化酶原中的蛋白水解激活位点惊人地相似。序列比较表明O.黑尾天蛾serpin-3是天蛾sexta serpin-3的一个明显的直向同源物，天蛾serpin-3是一种确定的黑化反应负调控因子。Serpin-3 mRNA和蛋白水平在细菌或真菌注射后显著增加。重组丝氨酸蛋白酶抑制剂-3以浓度依赖性方式有效阻断幼虫血浆中酚氧化酶原的激活。它与丝氨酸蛋白酶13（SP13）形成SDS稳定的复合物，并阻止SP13切割酚氧化酶原。将重组丝氨酸蛋白酶抑制剂-3注射到幼虫中导致真菌诱导的黑色素合成减少，并且减少脂肪体中的attacin、天蚕抗菌肽、gloverin和肽聚糖识别蛋白-1基因的表达。总之，丝氨酸蛋白酶抑制剂3在调节O. furnacalis larvae. (C)2015爱思唯尔有限公司版权所有。
Serine protease cascade-mediated prophenolxidase activation is a prominent innate immune response in insect defense against the invading pathogens. Serpins regulate this reaction to avoid excessive activation. However, the function of serpins in most insect species, especially in some non-model agriculture insect pests, is largely unknown. We here cloned a full-length cDNA for a serpin, named as serpin-3, from Asian corn borer, Ostrinia furnacalis (Guenee). The open reading frame of serpin-3 encodes 462-amino acid residue protein with a 19-residue signal peptide. It contains a reactive center loop strikingly similar to the proteolytic activation site in prophenoloxidase. Sequence comparison indicates that O. furnacalis serpin-3 is an apparent ortholog of Manduca sexta serpin-3, a defined negative regulator of melanization reaction. Serpin-3 mRNA and protein levels significantly increase after a bacterial or fungal injection. Recombinant serpin-3 efficiently blocks prophenoloxidase activation in larval plasma in a concentration-dependent manner. It forms SDS-stable complexes with serine protease 13 (SP13), and prevents SP13 from cleaving prophenoloxidase. Injection of recombinant serpin-3 into larvae results in decreased fungi-induced melanin synthesis and reduced the expression of attacin, cecropin, gloverin, and peptidoglycan recognition protein-1 genes in the fat body. Altogether, serpin-3 plays important roles in the regulation of prophenoloxidase activation and antimicrobial peptide production in O. furnacalis larvae. (C) 2015 Elsevier Ltd. All rights reserved.